(despite being a harem with a harem ending haha, the tag is there for a reason)

For example, stowaway in a plane lol. Also killed a whole imperial family including the kids cuz they were killing people in Earth.... he saved their citizens though

The ending is an example of this. It was anticlimactic but it fits. I mean in context, if you make a Level 999 gear to beat a Level 99 monster, with leeway to spare just in case a Level 100 monster shows up, of course you will win lol. Plus I think the epilogues nicely tied up the story. Another earlier example that I like is what happened in Reta's case. He does hope that she is good and hence treat her as such but at the same time he also prepared a backup plan on the chance that she is not what she seems.

For example he killed Hellinea (tho he "revives" her later though she seemed to bear goodwill but he doesn't trust her (he subordinated her with "Rule" after the revival), he also killed Spiera even though they had some sort of friendship previously because she agreed to abandon Earth.

My favorite side characters actually include the harem members lol. So yes it's that good. Heavier spoilers ahead.

Orochi for the bromance (also gets his own romance with Mystic later on). His relationship development with Ilhan is great.

Yumir for the cuteness.

Liera is best girl. The most loyal and the one who stayed by his side the longest (for 1000 years+). She prioritizes him. The scene where she was ready to sacrifice her life if need be to save him when the Chaos Will attacked was beautiful (falling angel wings and all) since she was both badass and touching at the same time. I also love his relationship with her (it's cute). He trust her unconditionally and it's obvious that he was affectionate towards her (even before their romantic relationship was confirmed... It was just that we weren't sure if it's a romantic affection or if he saw her as more of a sister). I mean he repeatedly thinks she's pretty and implied as much (that other human woman is not that pretty since he already spent a lot of time with Liera) and every time he meets other angels he'll ask about Liera and implied that he wanted to meet Liera again. He trust her and she trust him too. Honestly loved their relationship development and their relationship itself (hence why I was not keen on the harem ending but oh well).

Erta has the best retorts. Seriously her comedy is top notch and fits well with Ilhan's wittiness. I think she is easily one of the most likeable characters (Ertawagon is also an ongoing meme since she basically gets the information explanation role lol). Her relationship development with Ilhan is pretty believable too (I honestly thought they would be great as just close friends too though. But I understand the authors' love of harem).

Na Yuna had one of the best developments. At first she's just the annoying immature narccistic cute type, but as you get to know her, she showed more depth. She felt shallow (and her interest in Ilhan also felt shallow) at first but it got deeper and more genuine as time went on. I also liked that Ilhan didn't like her at all initially (her personality is not great lol) but appreciated her in the end due to this development.

The other harem members felt less developed tbh. More like the authors just cram them in? But they don't take up too much screen time so it's fine (most of the romance scenes focus on Liera anyways who is best girl. Ilhan reciprocated her first too and if she doesn't allow it, the harem ending wouldn't have happened either).

Kang Mirae had decent-ish? character development and gets the OP Mage role. But her relationship development with Ilhan seemed a bit forced initially (later they elaborated that it's because she felt like he was similar to her in a sense) as her affection went too deep too fast. Tbh I find her the most bland in the harem. I'm so glad the author change the female lead to Liera (there were rumors that the initial female lead was supposed to be Mirae aka The Empress).

Hellenia simply had less time than the other harem members since she showed up much later in the story. Her character (and the development) is interesting though. So I find her entertaining at least (and I find her affection for Ilhan believable.... him to her not as much but I guess it's because of her power of charm?)

Spiera had some relationship and character development but I didn't find her likeable (at least she's not bland).

The thief elf whose name I forgot (Phiera?) came out of nowhere. She seemed like a minor side character. If they wanted an elf, even Pate (well he's a male) had more development than her. But it's in the epilogues (essentially you don't have to read it) so its fine I guess. I guess author just wants to cram in all the harem.

Essentially the main story ended with "open-ish" ending for the harem since only Liera was confirmed to be in a romantic relationship with Ilhan (he actually initially rejected the other girls romantic approaches since he is already in a relationship with Liera which I appreciated....I really didn't want a harem ending due to this but sigh what do I expect from Toika, at least he said that he will always love Liera the most). The epilogues covered a soccer team made out of the harem members kids though so yeah the ending is harem.