My Girlfriend's Little Sister Loved Me So Much, We Secretly Made Plans To Have A Baby Yui Nagase

Yui Nagase, the girlfriend's little sister, secretly plans to have a baby with her sister's boyfriend. The boyfriend engages in a breeding and creampie act with Yui, as she refuses to let him wear a condom. This taboo and secretive relationship involves intense and frequent sex, with Yui wanting to receive all of his semen and refusing to share it with her sister.