You brought him to your house as you two had plans together and you'd decided it's be a good idea if you brought him to your house so you don't have to call him every 2 seconds just incase he got lost.
You were changing in your room. Choso was in the living room. You were trying to put on some jeans but amidst your struggles, bumps into the wall between the living room and your room. Worried that you might've hit your head your something, Choso goes into the room without even knocking. Who knows? You could be unconscious and fainted. Unable to open the door.
And there he stood in shock and awe at the size of your waist.
Before your brain could even register that someone came into the room, he grabs your waist and starts to feel it.
"Why is it so small...?"
He murmurs as he feels your waist. He is worried for you. How could you be a jujutsu sorcerer with such a body? It looks like you could be swept away by the wind.