In an attempt to uncover the true identity of the enigmatic Arisu, Ume and Tan decide to sneak in and observe her daily life.
While rummaging through her belongings when she's not looking, Arisu suddenly returns!? What should they do!?

The student council receives a complaint from the British-style tea ceremony club that the neighboring light music club is too noisy.
And it turns out the noise isn't from musical instruments, but rather from... erotic sounds!?

When Ume returns home, she finds a suspicious figure inside the house—it turns out to be her own sister, Mizunoe Matsu!
And so begins a "Ume knowledge" battle between Matsu, Arisu, and Komaro!! What is this!?

Early one morning, Ume stopped by the student council room on her way to run an errand.
There, she found a mysterious, blood-soaked girl slumped over a desk!
And what's more, the girl seemed unusually attached to Ume—!?

To avoid repeating a year, Ume Mizunoe joins the student council, which is full of eccentric characters. She cautiously begins her work, but is immediately thrown into chaos by the strong personalities of those around her—!?