Bijukubo "Iyarashii Kaa-san de Gomenne..."

Yohei lives happily with his 'mother' Kaho and cousin Fumika. But one day, Kaho reveals she's actually his father's older sister, not his birth mother—who passed away long ago. Shocked, Yohei begins seeing Kaho as a woman. Soon, a woman named Ikue moves next door. When she sees Yohei, she bursts into tears, and Kaho turns pale. Ikue claims to be a relative of Yohei's mother and wants to adopt him. Kaho and Fumika refuse. From that day, their lewd and erotic life begins...