Itazura: Ijiwaru Tenshi

Ayumi is a high school student who meets Shouma, the younger brother of her friend. Despite being younger, Shouma appears older and attractive. He quickly asks for Ayumi's phone number and acts charming, though he isn't her usual type. As they spend more time together, Ayumi begins to develop feelings for him. However, she questions whether Shouma is truly an angelic presence or simply someone who enjoys teasing others.