1) Selling his fancy high quality cookware and paper at dirt cheap prices. Sold at ~300k monies. Yet he literally sells 20 pennies for 3 MILLION monies just a few days later.... that cookware's probably worth a lot more AND he could've used it in his plans to make soap.) This mistake is excusable since he just got there and didn't know anything. But I would've still kept the paper just to jot down my notes/ideas/process in [Japanese] to keep my ideas straight & keep New Worlders from knowing what I'm planning.
2) Creating his product in plain view of everyone outside the damn castle. Great way to get your simple idea stolen. Inexcusable. There's no copyright protection. He could've simply burned the wood outside and made the soap in his room or something. (as long as he's using no/low-smoke heating.)
3) Giving away his first bar of soap at manufacturing cost. Wut? MC already knew soap is a luxury good. Realistically everyone's going to expect ridiculously low prices (seriously, who wouldn't brag about receiving something like super fancy perfume for $1?) Derp. Besides, he was dirt poor, at least turn a profit on it to cover a meal/inn cost or something.
4) Telling his newly gained slave the entire manufacturing process and requirements. She just met you, literally nothing's stopping her from just taking the process and selling it to the loanshark for her freedom & 10 million monies. Derp. Even the loanshark realizes he could just force a slave/future worker to tell him the manufacturing process. Should've just left the slave to burn firewood for the ash/ask around the city for sources of ash (since it doesn't seem like the citizens are using it for anything).
5) Buying a damn plot of land AND a factory on literally his 2nd day in business. Holy carp you farking moron. Should've just stuck with the stall idea and bought a RESTAURANT to obscure your manufacturing process/requirements (since a restaurant can easily use salt, oil, and firewood).
6) Telling a freaking loanshark the exact manufacturing cost. He's a damn loanshark, he doesn't need to know how much profit you're turning. That's just asking to get robbed later down the line. Better to keep costs/profits a secret so people mistakenly believe you're barely turning a profit --> Less likely for your entire operation to be seized. Hell, I would've just BSed it by claiming it's a re-manufactured bubbleberry product to make it more believable/obscure my process or by claiming it's made by some unique talent/blessing only I have (Thus ensuring my safety/discouraging theft).
MC ends up in apocalyse? Oh good, super competent sidekick also acts as walking exposition and tells me everything I need to know. Magical superwatch gives convenient excuse as to why I'm able to pull out my Supermarket supplies. MC was dumb enough picked up a token female that isn't even a cultivator & can't even fight zombies? Presto, now she's magically a cultivator.
He literally ate just two of the lowest grade crystals and is somehow able to beat up the thugs that even his sidekick explicitly admitted had higher fighting power than him. (Ch 8: They only know how to bully ordinary people. If not for their fighting strength being higher than mine, I would definitely go sort things out with them.”) IIRC, Ch2 makes it sound like his sidekick is a rank 1 cultivator since he's fat (able to feed himself --> afford crystals) & out hunting without weapons.
The apocalypse watch. He knows nothing about it, is aware that it'll take his info, can store & basically warp crystals (presumably other things) across the world, AND IT'S CONNECTED TO THE INTERNETS.... Better strap it on immediately and start storing valuables in it. Wtf? Dude, your superpower literally makes it nearly useless. Ch 12 even gives a good reason NOT to use it. The only security measure is apparently DNA.... So if someone holds you down & presses the button they can steal all your stuff? Yet he still dumps supplies into it. Even worse, if DNA is really the only requirement, they can just hack your arm off.
The MC is a mass of contradictions.
1) MC is set up to be a guy with common sense & military training. Gets caught up in danger, wisely decides to runs from danger, danger finds MC anyways, hero saves MC & takes him away from danger, MC stupidly runs back into danger, same hero has to save MC again resulting in fatal wound to hero.... MC decides to run away from danger again......
Then it copies MHA's first chapters almost identically: MC spots helpless child in danger, realizes he's just a normie and decides to run since he's got no way to fight, right?....... NOPE, can't run away, he decides to run straight at the monster and......punch the monster with his autistic self. Wut. Literally went against everything the MC was built up to be. To be fair, the ring might be screwing with MC's head because the ring does release some sort of light/aura around his head later, probably keeping him dimwitted or something.
2) MC wisely decides to stay away from hospitals/government because he's got a from a freaking different world with a magical ring. Wise decision, for all he knows his organs might not even be the same as the people in this world. Yet immediately agrees to get checked out at the hospital by his new GF which he didn't have in his old world, wut. (This goes wrong immediately since Obvious-Evil-Guy immediately figures out something is up with his ring but keeps it to himself.)
3) Supposedly majored in Computer Engineering, yet can't do basic research. Gets a hold of a computer to look for information and does the equivalent of browsing reddit for the day. Wut. Why the hell wasn't he looking for basic information like what the hell magic is, where heroes came from, and how to use his powers?
4) Goes to school, decides to keep a low profile since his otherself doesn't have hero powers (according to token GF)..... immediately decides to explode the training lizard. Wut.
Along with many other examples.
BUT...... it's not only the MC that has issues:
Token girlfriend, she's basically only there for exposition yet she never fights alongside the MC. She magically recognizes the MC is the silver hero even though this is his first time transforming, he said nothing at all in his interviews, & his otherself has NEVER manifested any powers. How the hell did she figure out it was him? She's apparently a B rank hero yet never shows up for any of the fights, suspicious since B ranked heroes are usually called upon the most to fight, with C/D heroes doing support work (the big 2-wizard fight is excusable since the battlefield was large & maybe she was somewhere else, but what about the other battles?). She agreed MC's probably from a different world since he can prove he's not the same person she knew (he was basically transported to this world, has knowledge of computer engineering (majored in Comp Engi in Uni, but his otherself majored in Heroing), has superpowers unlike the person she knew, & is literally wearing a magical ring that can't be removed. She agrees to answer all his questions yet leaves out some of the most basic questions anyone in the same situation would ask.... such as "WTF is magic/heroes and how do they work?" or other such simple questions.
Ironman: Supposedly a rank D hero, literally nothing special about him but his tenacity. Magically gets upgrade to a powerful monster detector that can detect monsters better than the MC (rank A hero) or other heroes can.
Likewise the military/news reporters: They've been fighting neighbors monsters for how long? They've proven cameras work (just wireless transmission of info gets screwy due to mana apparently), so why aren't they using long range methods of gathering information like satellites, drones, etc? Instead they face the same issue with every monster attack where they stupidly attempt to set use wireless, gets interrupted, then struggle to put up "wired" communications. Holy crap, at that point why aren't they just going the Evangelion route and simply wiring the entire place up? They've explicitly stated that they've managed to segregate the city into "districts" because apparently that keeps the neighbor gates controlled, why couldn't they just have wired cameras already setup?
Even the monsters themselves aren't consistent: Apparently even the weakest monster is resistant to conventional firearms, this is why heroes are needed & the military doesn't just bulldoze them with tanks or antimaterial rifles. Yet a news reporter manages to significantly damage a Wizard (supposedly a Class S threat) with a really big gun.
"I felt like I'm reading a actual spider with a human intelligence not a human reborn as a spider" - Scandalf.
1) MC knowing he can't release too many technologies (asks if patent systems exists, knows current world golems are poorly made things) and has enough common sense to render his potentially compromised warp gates inoperable at the start. Yet he completely forgets this and goes around tossing around innovations left and right without building any anti-theft safeties into his new innovations like the warp gate has (how difficult is it to have his plane/boats/golem have the same option as his warp gate?..... why is he making all these planes and ships operable by anyone?)
2) Supposedly magi craft meisters are shunned during the predecessor's time and there is only one magi craft meister at a time.... yet said magi craft meister is extremely powerful, wealthy, and has access to highly advanced technologies. 1, 000 years later somehow magic craftmen are all over the place with regular non-magi craftmen nowhere to be found (still haven't met a non-magic craftsman magician 5 volumes in....) The author claims the war 300 years ago wiped out a significant portion of the magic population but that wouldn't explain why magic craftmen became so popular or why non-magic craftmen magic people are nowhere to be found.
3) Supposedly writing magic formulas in Japanese makes them more efficient and would be an excellent way to prevent others from stealing his work (Having a self destruct option like the Terminator CPUs when the magic plate is opened up or something would be very effective, right?) Yet either the entire world can either magically understand Japanese or he just forgot all about this.
4) Apparently swords are a thing, but flint/firesteel aren't? A stupid way to make MC's "lighters" popular. MC also apparently completely forgot about his magic stone powered stoves he made for the village which would make lighters completely unnecessary. (Since they can literally run on fragments of fire magic stone dust found in a river bed.)
5) Current world golems suddenly gain a level in technology during the boat race ark. Apparently golems are rare, hard to make things yet all of a sudden an entire city has boat racing competitions with custom made highly advanced golems (Reinhardt made Lorelei which is somehow an autonomous golem which are supposedly very difficult to make, wut?)
6) Magic craftsmen also gain a level in technology during the boat race arc. They can suddenly read the orders/mana signature of enemy golems to figure out their directives and who sent them. Wtf? Why was this not mentioned/done during the 3 volumes that came before it? Why the balls didn't he do this when Gen/Gon first attacked & he re-purposed them?
7) The various villains are extremely stupid. I guess common sense fell drastically along with the technology/magic levels of the world. Supposedly Magic craftsmen are very rare and precious commodities being jealously hoarded by various nobles yet Dumbarse McNoblederp tries to rhape the magic craftsman chick MC was providing blueprints to. Supposedly she's the apprentice of a famous local magic craftsman which makes it all the weirder than said noble would try to rhape her. The village villain is yet another dumbarse noble that tries to manhandle the MC even though the King is trying to curry MC's favor. (How the hell do you fail that hard in your mission) ? The boat arc villain is dumb enough to leave a crapload of evidence (literally left 4-6 golems with his signature and very clear sabotage orders.... in a city filled with magi craftmen that could read said orders/signature if they got their hands on them, wut?)
8) Around volume 4 when MC is making his robot army author claims "Knowledge transfer is not effective in transferring knowledge to other humans." Yet he literally received most of his knowledge from the previous magicraft meister via knowledge transfer.... and has been employing it with very little problems. The only downside is that it's like having a "book" memorized in your head to reference. But that's still PRETTY DAMN EFFECTIVE. I'd love to be able to download books directly into my brain.
9) MC drops a bombshell about magic (apparently everyone has a limited amount) as late as volume 4 chapter 6. (Prompted because of Reiko's concern to him)...... then it's brushed off because the MC has a magic body which can absorb ambient mana, so it's okay for him. Wut?
Mecha Gi Ga and Hasu will save the day. \O/
Surprisingly being trapped alone in a magic-free zone for 3 months actually made him less retarded.
Seriously, a better way of setting up the first ~15 chapters: MC reincarnates as a sword --> Gets wielded by a goblin who he really dislikes but has no other choice (because he's literally a sword) but can't do anything about since he's getting exp/skills/stones --> Goblin becomes the strongest in his den & ventures out due to overconfidence (or tricked by MC into going out) --> Goblin gets too cocky and killed by another stronger creature (cannon turtle or whatever) --> Gets knocked away by the blast & accidentally kills a floater creature granting the floating skill --> MC starts life as a slowly floating spell casting intelligent sword --> start of the rest of the story.
For example: He has no problems using modern knowledge to build his underground empire & actually has his sensibilities kick in whenever his subordinate points things out according to "their" sensibilities (So clearly the Ryou portion is still quite lucid & influential). Yet the next moment he's absolutely flabbergasted that the protagonist reincarnator is speaking against slavery to a noble. Wut.
A) MC is supposedly hidden weapon/poison master. Fails at poison until ~100+ chapters in. Author remedies this by asspulling a cultivation/herb treasure trove for MC to loot. Miraculously the title duolo (Dugu) protecting the cultivation/herb treasure trove is a complete moron & can't recognize most of the herbs there.... yet somehow another title duolo can recognize several of the herbs several chapters later just by the effects they had without even seeing the plants themselves. Wat. (To be fair the other duolo is from Spirit Hall which has more resources but the sheer ignorance of Dugu doesn't make much sense except to give MC a reason to loot the herbs without Dugu murdering him on the spot.)
B) MC's stated multiple time to be ruthless in preventing potential future problems, the Tang Sect motto: "pull out weeds by the roots"....in practice almost never does this. In fact he almost does the complete opposite by almost killing the door guard of his first academy. (Stupid moron didn't have the strength to pull them roots at the time), luckily Grandmaster stops him. The closest he's come to actually following the Tang Sect motto with Blue Sunshine sect doesn't count, he stupidly talked about the missing leader IN FRONT OF A TOURNAMENT AUDIENCE.
C) Tang San & love interest make a duo team..... Everyone and their mother already knows their name & faces. Yet Grandmaster decides to force them to compete in 7 vs 7 team battles slap a mask on them, & even uses the school's name for their competition name yet suddenly nobody knows who they are even though they kept the same tournament name & are using the same abilities... Anyone with half a brain should be able to figure out the identities of all 7 just on those pieces of info alone.
D) MC had been told to only use his second spirit when his life is in danger. Proceeds to show it off in a crowded tournament setting. Likewise his hidden weapons are displayed constantly to his enemies. I don't think the author understands what the "hidden" part of hidden weapons is suppose to mean. Hell 180+ chapters in & Oscar is the only one to properly use hidden weapons (since his targets all die.)
E) Hidden weapons don't need copywrite protection since it takes a minimum of 10 years of training to assemble.... Orangutan Blacksmith proceeds to flawlessly disassemble and reassemble a hidden weapon "10x faster than Tang San" on first try. Tang San should've been going crazy at this revelation but he doesn't bat an eye.
A) Xian Wu's sudden clumsiness.
Xian Wu's true nature can be detected by Title Duolo level characters yet isn't detected by the various Title Duolo's that kept appearing early on (such as Tang San's father, Dugu, Bone/Sword who kept on eye on Rongrong, Chrysanthemum Duolo, somehow all of them missed Xian Wu even though she had no anti-detection cover until Tang San gives her the love flower & Chrysanthemum even held the flower yet didn't detect her. Of course Xian Wu clumsily drops the aura covering love flower at worst time allowing Spirit Pontiff to immediately detect her as a spirit beast. This makes no sense since she's a close combat/agility Spirit master.... Why the hell would she even fumble for no reason like that?
B) Spirit Pontiff's tactical retardation:
Supposedly the Spirit Pontiff rose to power with her cunning/overwhelming power to win over the others in Spirit Hall. Yet she's a complete moron. Instead of holding the entire MC team captive for harboring a spirit beast she inexplicably lets them go. Supposedly this was just to keep Grandmaster safe but that doesn't mean she couldn't just take them all for interogation & let Grandmaster go later. She also sends the Tang San assassination squad with orders to not release spirit rings for some ridiculous reason which gets several hundred spirit masters killed. Later on she also has 7k+ spirit masters die because of her tactical retardation which she's happy about....
C) Grandmaster's tactical retardation:
Stated above, has team cover up even though anyone with half a brain can already figure out who they are. Has supernatural ability to see the physical state of others & extremely broad treatment/combat knowledge (evidenced in training regiment of MC's team somehow new MC's physical limits even though MC practices a completely unique Tang Sect cultivation tech, also in the recuperative medication used, & knowledge of things that even Title Duolo's aren't sure about) yet keeps leaving MC to face mortal danger constantly (especially during tournament arc where he has two assassination attempts on his life.....)
D) Tang San:....... This is going to be way too long listing all the problems with his character. Basically everything but the biggest is his inability to follow simple principles/orders given to him by his Tang Sect/Father/common sense. This alone leads to most of the problems Tang San faces (and even the actual death of Xian Wu & near death of himself which ironically could've been avoided if he simply followed the Tang Sect way).
In this case the male half is a skilled sword/melee fighter while the female half is skilled in almost all magic except "space" magic (presumably they'll link up to fight together later and the dude half will cover that weakness).
There are several slip ups such as his teammates somehow being aware of his darkness powers before it was revealed, or little witch joining their battle team. Which doesn't make sense as she was already in another team... what kind of tournament allows for even opponents to swap into each other's team? Their team didn't even have much to gain from it since they already entered the top 4 and could've just surrendered. Also almost immediately after they accept her, the MC swapped his cult tech for a ton of stuff & unlimited access anyways... so basically he risked his team just for a bit of gold since Zong armor sets (for his teammates) & materials could be easily gotten as he can come and go as he'd like.
Also don't be surprised when the MC stupidly explains his trump cards out loud to his enemies immediately after he uses them. He became stupid when he started showing off his abilities, especially in the tournament setting.
He's already defeated the demon lord & died doing so in the old world....
She's only powerful due to some horrible human experimentation & only has a few months to live.
MC is basically spending his current life as an extended vacation since his past life was wasted dying to save the world from the Demon Lord. He's pissed off at the temple folks because of their "holier than thou" attitude they use to justify screwing him over in his past life by throwing him at the Demon Lord (which resulted in MC's death)...... and have the same attitude here..... and try to throw him at a Dragon in this world. Not surprising he'd be pissed off at the temple folks. Seriously, they literally use the excuse "the goddess asked so you have to do it."
His past life blessings (practically the Triforce of Courage) has followed him to this life & he practices an abnormally powerful cultivation..... errr "mana breathing technique, " MC has been stated to train discretely, & spends a lot of time "out of sight/playing hide & seek". This is why he could basically kick around the assassins (even though it was difficult since his physical body explicitly couldn't keep up). And powerful mana has been literally stated to grant supernatural physical abilities (mana sword, cutting spells, sensory abilities, hiding abilities, physical boosts, and sword throwing). Seriously, even a dragon calls him a monster & refuses to teach him magic out of fear of how powerful he could become.
Riley is like 16 years old or something.
Problem: Because MC's mother is so ridiculously kind to him, MC feels obligated to let her be proud of him but still doesn't want anyone else (rest of family) knowing his skills/power. MC also knows that MC's mother is literally a fighting novice so she wouldn't really know how amazing her son is..... Ian was the Mercenary King & literally spent almost Riley's entire life suspecting him of great power/abilities. Apparently that's why he's so faithful to MC. Sera is also a very trustworthy maid of his mother.
Solution: Get Ian & Sera to confirm to her that Riley is amazing. One was a former Mercenary Hero, the other is a trustworthy & competent personal maid of said mother. If both of them say Riley is amazing, even the mother will get a pretty good grasp of how amazing her son is.
For those harping about the romance, keep in mind the MC's got a mind that works many times faster than "normal" folks, a dulled sense of emotions (dude isn't a happy guy & feels life is meaningless since he was 6), and suffers from manic mood swings among other mental issues (Part of his "acting", the best lies are mixed with truth after all). He's also using s*x as a tool (Such as Barbatos making her think she's in control, etc) which is in line with his character. Because he wants to be King of the Pirates~ I mean "everyone".
He's also not falling in love "too fast" remember he's already played though the game & knows the personality/intellect of virtually every major player. His chosen harem "click" with him intellectually and/or emotionally. In fact he's falling in love SLOWER than most xianxia protagonist who fall in love as soon as they see the damsel in distress.
When you have the MC literally slap around one of the strongest beings in the world as soon as he appears..... then have him power up EVEN MORE, that prevents any decent story telling as all suspense is lost unless the antagonist ass-pulls some stupid power.
Yet another reincarnator novel where the world can only exist due to the sheer stupidity of its denizens. (Literally nobody except for reincarnators have decent combat knowledge.) Handwaved by claiming they just "relied on the goddess blessing too much" which quickly falls apart when you realize there's actually an adventurer's guild that nearly everyone is already a part of who routinely fight to-the-death battles against strong monsters without goddess blessings.....
For example: Getting magic power/class, MC snuck into the summoned's group again so he can get a magic class because apparently magic academies & organizations won't let him in & he's scared they might have someone/something powerful enough to see through his deceiver's veil.... Then the author promptly forgets about this and has the MC directly enroll in one of the top magic schools. Wat. Author also has the MC sneaking in all manner of places without fear of discovery (dumb MC goes around using his real name and face). Wut. It would have made much, much more sense if the MC decided to join the summon'd group because he knew of the 7 hero shrines and wanted to snag the legendary hero magic class (es).... Chapter 1 & 5 makes it very obvious he wasn't aware of such which makes his future actions ridiculous because he could've just derped around sneaking into magic academies, tricked demons into giving him their stats (gambling), and steamrolling through their quests/missions like he later does at Airfruit.
Also like NoobaLoob said, people are willing to help out the MC left and right as long as he doesn't reveal his identity to them, even after he does, several are still willing to help him (or at least not attack him outright) as of c106 which kills the credibility of MC's backstory.
Turns out the higher ups crafted most of MC's bad rep on purpose since they actually don't want the demon king dead due to the numerous even worse calamities that follow. This is plausible as there is no Internets and it would be fairly easy to spread false rumors widely via authorities in a place with middle age tech. Especially as everyone takes the status window as law.
MC also isn't just hauling a half decent mage or scrolls to defeat the demon king since he's aware of the future calamities.