When Isaac was made Lord of a corrupt and decaying city where he'll be executed if the city does not profit, he instead turned it into a Las Vegas with legalized vices such as casinos, high class prostitution and other types of entertainment. He fooled the syndicates and reined them in but still allow them to run the city however made it mandatory that children must be fed.

When the city became prosperous and was attacked by a Duke hungry for the profits, Isaac became an arsonist. The city does not have walls nor a standing army so he barricaded the slums, lured the enemy army in and set the city on fire burning the army to death and also a quarter of the city. Now he can develop the slums at lesser cost too. When the emperor questioned him about the arson, his answer was if he was gonna die and lose what he had built, he might as well destroy the city so no one will get it.

Isaac allows his subordinates and partners to embezzle state funds and told them to make sure its not too obvious but he actually uses it as blackmail material to control them.

When the emperor tried to strong arm Isaac into being his minion, Isaac puts out impossible demands, stabbed a royal guard in the neck and casually inform the emperor that he should be prepared to pay the price if he wants to make use of Isaac.

When promoted to a Director of Security and had to set up a team, Isaac told the council he does not need agents and soldiers who are spies or traitors from other factions. Instead he needs dogs who would follow his every command. On the first day of training, Isaac opened fire on the recruits (elites from other divisions) as a form of survival training, ended up killing/crippling a few which triggered the observers into stopping him but they got relieved of command for intervention as Isaac planned. He then proceed with ranger training (like forcing them to eat food thrown onto the muddy ground, basically like dogs. Yes, this is actual ranger training for those who've never served in the military before, youtube and wiki ain't gonna show you all the nasty stuff) for these recruits to pit them against each other as he was banned from direct killing.

When deserters tried to escape, Isaac blew up the airship killing them and also losing the only transport for retreat. However its not on a whim as unbeknownst to many, there were traitors and enemies within the ranks.

When the portal opened and the world was about to be invaded, Isaac ordered his team to fire into the portal to bait the enemy to send in the armored column instead of soldiers. He had dug a hole in front of the portal and the tanks end up being crushed on top of each other and buried in the hole. He then executes an enemy officer in front of a captured surveillance drone as a welcoming message.

When the Heads of other departments send their messengers to invite him, Isaac shot the messengers and send them away to inform their bosses to come in person instead of sending lackeys.

If you really hate harem, just don't read the second half of the side stories. The side stories itself are not crucial for the main plot, as they're supposed to satisfy your curiosity about things not being told in the main story. For example, the past of someone that doesn't make sense if the author forcefully try to explain about, so the author just told them over the side stories.

In fact, the epilogue is a plot twist too. The clue of it came from unexpected place, because it's small enough to miss.

before he goes to the otherworld

Overall the MC is beeing described pretty good during an exchange in the first arc between a girl that can see the true nature of others and our MC:

“... Lazy.”

“Lazy? I think that’s perfect.”

Isaac laughed once more, but Kunette hadn’t finished speaking.

“... Lazy. A lazy, sleeping monster that has shackled itself until someone bothers it.”

“... ”

Isaac had a complicated look when Kunette finished her words.

“Monster you say? Well, I guess you’re right. But none of it matters if nobody bothers me right?”

First off, the entire gambling to win the waterways strat was amazing. enjoyed every second of it. Next, the scene where he's just massacred a whole group of knights and then central shows up. And, Shockingly Reisha is on there side!?!?! What will our MC do after realising that one of his few 'close' acquaintances is on the side of the organisation which literally just kidnapped him!? What else other than point his crossbow at her and pull the trigger immediately, with a reaction that amounts to "oh look, another target". My sides almost split from that.

Oh, also that time where Rivelia was the only one who asked Isaac if he was doing alright after the kidnapping incident was way more adorable than it had any right to be. The ship would be sailing immediately in almost any other novel but unfortunately the hull has a couple holes in it called "Rivelia's absolute hatred for Isaac" and the port's crew are not going to patch it up.

It's also really interesting how Isaac keeps using 'Hero' to refer to Rivelia. Especially with how it almost seems like he's trying to fan her hatred of him to even greater heights or showing her exactly how f*cked up people can become by using himself as an example. Perhaps it's going to end with her killing him after he becomes known across the world as the insane heartless slaughterer that he is? He does put an emphasis on how it's not when you die that matters, it's how you die. Or he could just be acting like he usually does, I cannot tell but I like to think about it.