Keishi Harumoto 東本桂士

Shortly after advancing to the high school division, he became a recluse and rarely shows his face at the academy.

He is eccentric and intensely dislikes people; consequently, he seldom leaves his room. He communicates solely with Mizuki, a longtime friend.

An expert in IT, he frequently amuses himself by hacking into systems—such as the security cameras at Thrive Central—to observe people. Recognized for his skills, he joined the venture company run by the Mikami brothers.

Although he is technically a member of the Singing Club, he is a "ghost member" who almost never attends activities, remaining on the roster only thanks to Mizuki. However, he does seem to enjoy singing itself.