Keishi Harumoto is a male student at Private Amaka Academy, born on November 29th. He stands 168cm tall, weighs 58kg, and has blood type A. Living with significant hikikomori tendencies, he rarely attends school or engages socially, communicating almost exclusively with Mitsuki Akika. Despite this profound introversion, he shows a willingness to help friends when asked, provided the task doesn't require leaving his isolation or physical exertion.

Formally a member of the school's singing club, his consistent absences render him its "ghost member," maintaining a passive role due to his reclusiveness. His observant nature becomes relevant when the "government" directly contacts him, notifying him of plans to close School District 7 and renovate the worldview. This notice occurs because users, represented as white people and cats, are distancing themselves from the district. This impending closure coincides with Saku Otonomiya's rising prominence in the music unit "Sakutasuke," leading Kagura to pin hopes on Saku's performance in an upcoming singing contest.

He has a dedicated character song album featuring the tracks "Command 'HEART' Execution" and "Heart Democracy [Rearrangement]".