The manga adaptation of 'I Was Caught Up in a Hero Summoning, But That World Is at Peace' really shifts the focus toward Kaito's hilarious internal monologue and the absurdity of his situation. The original web novel's text-based humor is one thing, but seeing the sheer visual spectacle of the Six Kings fawning over him, especially the Demon King, adds a whole new layer of comedy.
Key characters are definitely Kaito, our bewildered everyman, and the so-called 'Six Kings' who rule this bizarrely peaceful world. The Lunar King, Alexia, is central to the early plot since she's the one who accidentally summons him. But for me, the standout is the Demon King, Lilliel. Her introduction as this terrifying, ancient evil immediately undercut by her becoming a lovestruck, blushing mess around Kaito never gets old. The manga panels of her trying to act dignified while clearly over the moon are pure gold.
You also have characters like the Heavenly King and the Spirit King floating around, each with their own quirky dynamic with Kaito. The real charm is how this overpowered cast, who could easily destroy worlds, are instead just... hosting him, trying to make him comfortable, and basically turning the 'hero summoning' trope into a weird, reverse-harem adjacent sitcom where the 'threat' is overwhelming hospitality.