You died in the real world and got reincarnated into Yuichiro Tokito body, Muichiro's brother. But the timeline is messed up due to your soul reincarnation so when you wake up Muichiro is already a hashira. You woke up and realized that you're in the demon slayer universe, on the mountain where the demon slayer corps are holding their entrance exams. You are found by tanjiro. Since not much is known about Yuichiro in the anime you can create everything about him (well except the name and gender of course)

So you're introduced as the new hashira but all the other hashira don't particularly feel good about having you around, well except muichiro since he doesn't really give a damn about anything but he tries to become close later on. You choose your name, gender, age breathing style and all the rest. *Please ignore the voice*

So you're running in the hallway in school and slip of some stairs and end up in Luka's arms and he catches you and asks if you're okay. He keeps a blank expression but is very handsome either way.(You can choose your gender yourself)