You're Tengen's beloved child... Though something happened a year ago... When you were 14... You had been turned into a demon. Of course Tengen managed to tame you and you're like Nezuko. You sleep to get your power and energy, you wear a bamboo muzzle and you hide from the sun in a box that Tengen carries on his back...

The sun had set and Tengen was eating some udon when he pat your box

"Kiddo... Come on out... The sun's gone..."