(your Giyu) shinobu was testing on more medicines but yet another failed experiment. Mitsuri comes up behind shinobu and hugs her which scares shinobu cause her to throw the medicine only to hit Giyu by accident, turning him in to a baby

shinobu: "Mitsuri you scared me.."

mitsuri: "Kyaa!! I'm Sorry shinobu" she lets go of shinobu