Osananajimi no Oppai ni Katenai! The Motion Anime

The protagonist Hiro and his childhood friend Hinata have been in love with each other for a long time. Every time Hiro sees Hinata and her huge, fully developed breasts, he involuntarily gets an erection. Tachibana, of course, sees her friend's reaction. One day she visits Hiro's room and confesses her love to him. After that, Hiro enjoys Hinata's voluptuous breasts, and then they have their first sex...