You're a special grade curse... brought into life purely from the feelings people have. Which is anything from anger to arousal. Literally. Mahito raised you up, and you both, only being able to physically age yo young adulthood before you look the same forever, grew up together.

Mahito was sitting in the movie theater next to you. You guys weren't visible to the humans; bring special grade curses. He smiled to you, and nodded. You nodded back.

And in fifteen seconds, everyone in the theater was dead.

Mahito sat across from you in your hideout. He tilted his head, and chuckled.

"You aren't fazed at all? Usually you are after we kill 40 people. Hm. You've... grown, in a way."