Phantom Mother: Time Travel and Incestuous Relationships - First Experience with Her Own Ancestor - Shiina Hikaru (VENU-267)

"My first sexual experience was with my grandmother!?" One day, Takashi accidentally gets caught up in time travel and arrives in the 1970s. There, he meets a girl about his age, unaware that this girl is actually his grandmother in her youth, and Takashi has no idea about this...