The original heroes turned traitor after defeating the demon king, so the original summoner, the princess, had to summon other people to defeat since she had no option. Sounds redundant and like a bad idea considering how they got into the situation in first place but hey, it worked.

He's basically a less tone down version of Saitama, he got too strong in the original world and just wants to have a blood boiling fight. So once he got the chance to fight people who are actually strong, he enjoys it. As to why he's strong, who cares. I mean shoving a tragic backstory or actual reason is unnecessary cause he's a simple character and I can enjoy that. He's happy about fighting strong opponents, he doesn't think with his d*ck and is a sensible person about interacting with other people well, aside from the absurdness to how powerful he is and the sh*t he can pull off.

The princess summoned people who had great imagination from our world who were in highschool. Sounds like hella bad choice to pick from. Cause let's face it, people in highschool who have great imagination are either aspiring artists or people with issues that fantasize a lot or both at the same time. And what do people with issues do once they have people, they get drunk on it after all. I mean the princess probably didn't expect that to happen considering they summoned people from another world before and no problem, if something works the first couples of time without a hitch, I can see why they would be surprise when it did became problematic the next time they did it. So don't get your panties in a bunch claiming they're idiots since we get see this from a outside perspective and know that half the damn time highschoolers are punks.

The rest of cast mesh well together and the conversations don't feel forced, the romance is light hearted and vanilla, but it's not overbearing that it gets in the god damn way. The princess is naive and young, but that what a sheltered princess is. Not every princess can be a hardcore sad*st or some super intellectual. The other two people that were summoned to help the MC are similar to the MC in regard that they're not normal in our world, so they're able empathize with each other and can get along well quickly. The princess's aide doesn't get much screen time and feels like she's there to be poke fun of. I can see why since she simply gets outshined by the other three since they're presence is unique and she's rather ordinary aside from her housewife skills.