Houkago no Hisokagoto

Fuka is a high school student who became fascinated with the "world of Japan" after attending a tea ceremony with her grandfather, a Japanese confectioner, and now aspires to make Japanese sweets. She dislikes Tsujido Kaede, the most popular boy at school and whose family is a famous tea ceremony master. However, after school, in the tea ceremony club room, he shows interest in the sweets she has made, dresses nicely, and serves tea, revealing a more Japanese side to him that is the complete opposite of his usual frivolous personality...

(Source: Shogakukan, translated)