Welcome to the Succubus Sorority Turning into my Younger Sister's Little Sister
Description
"A man awakens to being a member of female incubuses. On the day that his sister brought friends to their home, he finds Yuna having sex with Kokona and Kokoa. Kokona invites Hinata to join them. Although Hinata refuses with his mouth, he ends up accepting Kokoa's blowjob and other sexual services. Without realizing it, Hinata's body begins to transform into a girl and his stance is also changed into that of Yuna's younger sister..."