Sakai, Mitsumune

酒井光宗

Mitsumune is the alias the main character uses on the online website.

Spoiler

Mitsumune appears awkward around girls and claims he is "quick to fall in love." He displays a righteous personality and clearly expresses his ideals. His age is not specified, but since he attends cram school, he is likely in his late adolescence to early adulthood.