Genshin Impact: Yoriichi Tsugikuni's Teyvat Journal

Yoriichi Tsugikuni feels like he got the wrong transmigration script. He closes his eyes, opens them, and finds himself reborn into a samurai family in Inazuma that's barely scraping by. Fine, so he's been reincarnated. At least his name is still Yoriichi Tsugikuni. As a bonus, he gets everything belonging to the legendary swordsman from Demon Slayer: Sun Breathing, the Transparent World, and the Demon Slayer Mark. The problem is, they gave these bonuses to the wrong person! In his previous life, he was just an ordinary office worker who played games and watched anime. He was cheerful to a fault, and occasionally a little devious. After spending twenty-five years in Teyvat, he thought that was how he would spend the rest of his life: practicing swordsmanship, teasing people, and occasionally musing over the legends of the Raiden Shogun. Then his older brother, Tsugikuni Michikatsu, went off the deep end in pursuit of power and, after being experimented on by that mad scientist from the Fatui, turned into something neither human nor ghost. Well, this is just great. Yoriichi Tsugikuni, Pyro Vision wielder, strong enough to go toe to toe with the Raiden Shogun, now has a new job: hunting down the Abyss Order and the Doctor all over Teyvat. In short, overtime. The sword at his waist is called Nichirin. It can't kill demons, since there are no demons here, only oni, but it works pretty well on monsters. As for the future? He'll take it one step at a time. That's just how he is: he laughs when it's time to laugh, and when it's time to cut someone down, he never holds back. (This isn't Yoriichi himself, just his abilities. His personality is closer to Tanjiro's. I originally generated this just for myself, so mistakes are only natural. I'll drop it when I lose interest in the subject.)