Having transmigrated into the world of Demon Slayer, Mugae became Muzan Kibutsuji's adopted son and became Kokushibo's apprentice to learn Moon Breathing. The young prince Mugae declared that with this identity, he could roam freely throughout the entire demon world!

Muzan Kibutsuji: He's such a filial son, I'm dying of filial piety. I never want to kill his father with Tamayo.

Domo: I treat Wuya like a young master. The young master always wants to treat me to wisteria flower tea, and he also likes to take me out to bask in the sun. He's so considerate!

Jade Pot: Young Master Wuya is a hypocrite. He says my pot is asymmetrical, but secretly he sells it for money!

Naruto: With Young Master Wuya's praise and recognition, my flute playing skills are getting better and better!