Oni mo Akureba Koi wo Suru

Gouki is a fearsome oni (demon) who is completely and utterly in love with a human named Fushimi, who works at a local donut shop. Disguised in human form, Gouki visits the shop daily just to see Fushimi's smile, perfectly content with watching over him from afar. However, his frequent visits lead to Fushimi recognizing him as a regular and striking up a conversation. When Gouki rescues Fushimi from a group of drunk harassers one night, their relationship begins to move beyond that of a shop clerk and a customer. It's a "100% purity" romance between a devoted, awkward oni and a kind, natural human.