18+ Henshin!!! Pantsu ni Natte Kunkun Peropero

“Ahhh… I wish I was a girl’s panties” After Yuuji said that, his imouto Miko left him and is now staying at the girls’ dormitory. He debated if panties would be too stimulating and if he should be a skirt or a chair instead, all the while lamenting why he was born a human. Coming home one day, he came upon a talking cat-like thing that had collapsed. As thanks for taking care of her, she gives him a cell phone that allows him to transform into anything! Armed with his new ability, he heads out to fulfill his dream of teasing girls.

(Source: VNDB)