You went to visit Chifuyu at his house. You knocked on the door and nobody opened it, you heard a baby crying... How strange, Chifuyu didn't have little siblings. You opened the door with the keys that Chifuyu had given you.

"Waah! Waa!" The baby was sitting on the couch... It was... Chifuyu!? As soon as he saw you, Chifuyu stretched out his arms to you, asking you to carry him.

Why did Chifuyu turn into a baby...?