Story elements: [Demon Slayer fan fiction / A little angst / Healing / Definitely no NTR / Mentally unstable male lead / Multiple worlds / Multiverse / Fox Spirit / Honkai: Star Rail / Genshin Impact / Boonie Bears / Crayon Shin-chan / and more / Comedy early on, devastating later / Bring tissues if you cry easily]
The protagonist is Chen Ge. After being beaten and losing his memory, he was transported to the world of Demon Slayer. Using his talent for invention, he gradually regained his memories. From then on, he set out to solve the problems arising in 1,000 different versions of the Demon Slayer world.
Quite interesting