Himitsu no Otsukiai wo Shiteimasu.

Takase, a second-year highschool student, is dating Togawa, a popular classmate. However, they're keeping their relationship a secret from everyone else. Togawa seems cool and collected in front of friends, but when all alone with Takase, he reveals his sweet side to her, which makes her heart race. But one day, their relationship is discovered by Kurono, a third-year student! And it seems like he's taken a liking to Takase...?! A sweet highschool love story between a doting boyfriend and a slightly clumsy girlfriend! (Source: MangaPlaza)