I Killed Ghosts and Gods in Tokyo High School

When I woke up, I became Yuying Shenya, my parents were dead, my sister had a house. I thought it was just an ordinary day in Tokyo, until that day I, sitting by the window in the back row, witnessed a shocking change at the school gate. "That's... A demon?" When the Demon Slayer's "Demon Slayer" awakens, the system prompts sound in his mind—— "This world turns out to be really different."