Found this Manga through viral Tik Tok posts I like the setup so far, a chill dude gets into a regular character from a game he likes. He is well aware of not altering the main storyline and attempts to refrain interactions with "main characters." Likewise, he utilizes his knowledge of the game to become very strong early on. Things don't go his way as he gets involved with the story line, etc. He is fairly OP but it is not unreasonable as this is the same as a gamer taking advantage of short cuts. What I do appreciate is his stance on keeping the game storyoriginal as much as possible.

Gotta respect a guy who is disciplined enough to retain his values