Yuki, Kurumi, Rii-san and Mi-kun are the happy members of the School Life Club. Their goal is to be in touch with the many things that one couldn't be exposed to if they'd only been in class. And to that end, they sleep at school.

The School Living club has new members! After bringing Mii-kun and Taromaru back from the besieged fort in the shopping mall, Yuki and Megu-nee take them on a grand tour of the school. For a moment, Mii-kun feels like life might just have gone back to normal...especially when Yuki decides to welcome her to the club by holding a field day event!

A swim in the rooftop "lake" leaves Taromaru covered in nasty green algae, leaving Yuki to give him a bath and the rest of the club to take care of her equally dirty laundry. As the four stand under the sun watching the clothes dry, the conversation turns to "graduation" and their plans for the future. Later that night, a bout of insomnia leads Mii-kun and Rii-san to search for the lock to Megu-nee's secret key.

THEY flood into the school as if attempting to take shelter from the torrential rain. The power has been knocked offline. The School Living club room is under siege. Kurumi is unconscious after one of THEM bit her. All alone, Rii-san prepares to keep her promise. Meanwhile, Mii-kun prepares to go to the emergency shelter and find the vaccine, but the thought of having lost Taromaru to THEM drains her will to continue. Just as one of THEM reaches out to grab her, she's saved...by Yuki?!

The School Life Club is in grave peril, as swarms of THEM flood the school.