Kiyoomi accidentally drank a random liquid from the cabinet, because it looked like water. That turned him into a cat boy. A small one to be exact.

When Atsumu got home, He looked for kiyoomi everywhere.

"omi-" "Ow!" A small voice said. Atsumu looked down and saw Kiyoomi. "watch where you're going!" Kiyoomi said, he was quite small.. Like a baby's height, and had a high pitched voice, instead of a deep voice.