Class no Inkya Busu?... Jitsu wa Cho Bijin Cosplayer Datta

Akira Hazama, a high school boy, hides his otaku nature and enjoys his school life as a cheerful person. However, he secretly goes to a doujinshi convention and has a fateful encounter with a..? (Source: Kodansha, translated) Note: Originally, 11 chapters were published in Suiyoubi no Sirius. When compiled into volumes, they were condensed into 6 chapters.