Masamune Sakurakōji, a third-year student at Aokisora High School, holds the position of student council vice-president. His duties include overseeing school clubs, enforcing regulations such as issuing yellow fine cards against dishonest recruitment tactics. He actively mentors younger students, offering guidance to first-years like Haruki Mishima and Towa Honda on navigating club recruitment and school life, demonstrating his observant and proactive support for underclassmen.

Masamune shares a close friendship and collaborative supervisory role within the student council with its president, Mikado Nakajima. He exhibits a protective attitude towards second-year student Natsu Asumi, often watching over him with a smile as Asumi prefers solitude. Masamune's calm and reliable demeanor consistently provides stability and support to his peers.

His surname, Sakurakōji, combines "sakura" (cherry blossom, also contextually meaning decoy or horse meat), "ko" (small), and "ji" (road). His given name, Masamune, derives from "masa" (right, proper) and "mune" (religion, sect, or essence). Physical descriptions consistently note he has black or brown hair and brown eyes.