Saku Hasumi stands as the sole first-year regular player on the Okazan Futsal Club roster. He projects a serious demeanor yet reveals cocky and innocent traits, frequently directing cheekiness towards teammate Ryutaro Sera in response to Sera's persistent bothersome behavior. Tokinari Tennoji selected him as a regular, recognizing his assisting abilities despite his freshman status. This opportunity fuels Saku's intense dedication, driving him to practice relentlessly with a singular focus on supporting Tennoji, whom he deeply admires.

His background includes middle school futsal experience on the second team alongside Yukimaru Kurama, who later attended Momomi High School. Saku has a younger sister. He stands 173 cm tall, sharing this height with Yukimaru Kurama, and his astrological sign is Libra.

His personal preferences include hobbies of dancing and listening to music, with dance noted as a special skill. He enjoys taking baths and favors BLT sandwiches, but dislikes insects and white rice.

The name "Saku" (朔) carries meanings related to astronomical conjunction or the first day of the month. His surname "Hasumi" combines "lotus" or "water lily" (蓮) with "beautiful" (美).