There is a certain type of japanese comedy where they are intentionally stupid and just play along with it, I think it's one of those things that you either like or you don't. Judge if you want to read this based on that first. Bottom line: Funny man accidentally badass in an uncool way but so earnestly that it becomes cool.

Isekai is currently the most popular genre in fantasy, to the point that we don't have just direct parodies doing the opposite of what's expected but a full range of absurd takes on the concept. You have the land of the failure that is Konosuba, you have cute girls doing cute things disguised as isekai with Watashi, Nouryoku wa Heikinchi de tte Itta yo ne!. And in this case you have the standard OP protagonist taking the chance to be the biggest chunnibyou* ever.

Unlike the crimson mages from konosuba that are comedic exaggerations of over the top dark heroes, we're supposed to be part of the joke instead of mocking them. The MC is living his life the way he wants and doing the most of it. When he spouts non sense badass lines he himself doesn't understand, when he worries if he's going insane for doubting a human can take a nuke one on one, or when he's training secret techniques to get his ass handed to him in the most background character way, the reader is supposed to laugh, clap and respect his way of life. He is a badass, not for the things he can do, but for his dedication to the most idiotic things possible. Everyone around him progresses in life while the invincible MC is playing pretend.

My main complain so far, with 15 chapters read, is that the initial joke where his chunni openly fake story happens to perfectly match with the huge conspiracy to take over the kingdom and destroy the world for no reasson. All the time we're seeing both sides of the story: his impression of what he's doing and how others see it; and the outsider perspective matches the world when his doesn't. That's the joke, he's brute forcing his fantasy into a working world. But the initial building block of the whole plot just happens, because. I assume that at some point it's revealed that either the world is being changed around him, he's responsible for everything bad happening, or some god implanted those ideas. But having that hanging is like a thread that needs to be pulled and I fear it will take away the fun when it does.



*Chunnibyou, or chunni, eight grade syndrome, is a term that refers to people who has self important power fantasies in 8th grade, made them public and maybe kept them in HS. For boys it's usually being a secret badass hiding a huge power (probably tied to an arm or eye) and for girls it's seeing the future or cursing people with magic. If they took it in stride it'd be just a thing they like, but being a chunni is tied to the embarassment from realizing how lame you were while trying to be cool. It's a pretty universal thing.