Inu mo Arukeba Koi ga Hajimaru

Sora Hometani is a student who transforms into a pomeranian when stressed due to his special physique. Until one day, Sora's classmate and secret crush Makito Matsuda sees Sora in his pomeranian form, and brings him home for his grandma to overcome her sadness of losing her old pomeranian Pometa...
Note: Chapter count includes an extra.