Kono S wo, Mi yo! - Cupid no Itazura

Rin, a 22-year-old, struggles with two significant concerns: a birthmark on his buttocks that he is deeply self-conscious about, and an unrequited crush on an older woman who views him as a younger brother. Since a traumatic incident at the age of 7, Rin has been hesitant to let anyone see his naked bottom, leading to a long-standing shame about his unique birthmark. However, his life takes an unexpected turn when he discovers that his birthmark may possess mystical powers, granting him influence over the opposite sex. This newfound ability raises the possibility that Rin may finally be able to turn his perceived flaw into an advantage, potentially transforming his relationships and outlook on life.