Leech Demon Yoichi is the most dazzling, eye-catching, and limelight-stealing character in "Light Speed Masked Man No. 21." His charm even overshadows the protagonist Sena's first supporting actor, the underground leader of the Demon Bat Team, and the pillar and core of the entire team. When he tortures people with all kinds of demonic behaviors off the field, and when he uses his unrivaled smart mind to do superhuman things on the field, what is he thinking in his heart? And what do other people, whether they are partners or opponents, think of this devil-like person?