[Invincible] (for the male protagonist) + [Main storyline: Honkai Impact 3rd] + [Single/Multiple female protagonists] + [Later, random travel to other worlds]
When a boy who has traveled to countless places arrives in a world of trees and sea.
He chose to join in, to become a part of the story, to experience it, to experience this "healthy, sunny, and positive" story.
"I don't really like tragedies in my notebook."
"Even the worst author can't write a story using the tears of a beautiful girl."
"Since I'm not satisfied with your story, then I'll have to write it myself."
These are the words this young man spoke to a certain being.
As the story unfolds, only the boy himself knows whether it is the story itself or the characters within it that attract him.