When I peeked at my girlfriend's younger sister changing clothes... I was instantly aroused by her huge breasts! She's naturally oblivious and not afraid of pressure, so I earnestly asked her, and she agreed. (Shino Mayu, SONE-754)

Memories of his girlfriend, her gentleness, her cuteness… all of that was instantly forgotten; the allure of large breasts was now being rekindled by the excitement surrounding his girlfriend's older sister's enormous locker room breasts.