まほ☆たまシリーズ ～おっぱい編～

Teacher Sakuya has her own understanding on japanese culture, so she cooks in the naked apron on the mornings. Main character takes bath with Miki and learns from her about Sakuya's big tits secret. Mei prepares a potion that makes any breasts enlarge instantly. It's exciting experiment time for any big breast enthusiast.

[From vndbreview]