Onijoushi no Yakimochi ga Kawaisugimasu!!

"Do you know about hickeys? They're great at repelling insects."

New employee Sayako secretly has a crush on her boss, Kuroki, who's a year older than her and a workaholic. However, Sayako makes a lot of mistakes and is always getting yelled at by Kuroki, so there's no way she could ever confess her feelings to him. Then one day, Sayako makes a mistake that causes trouble for another employee, and finally decides to quit. " If only I could do it before I quit..." Sayako impulsively confesses her feelings to Kuroki! To her surprise, Kuroki gives her an unexpected reply. "I'll go out with you." She thought he was just a "business boyfriend" to keep her around, but it turns out that Manager Kuroki is a serious boyfriend with strong possessiveness—!? Could it be that he's really, really in love with her...!?

(Source: Shogakukan Creative, translated)