Sigma is a member of the terrorist organization the Decay of Angels. Sigma is the quiet and gullible manager for the group and is often pranked or used by their colleagues. One day Sigma is helping their superior, Fyodor Dostoevsky, with a jail break. During this jail break Sigma turns their back on Fyodor and instead helps Osamu Dazai, the man being framed by Fyodor. Sigma helps Dazai with his jail break instead. While Dazai is on the run, Sigma confronts Fyodor with a gun.