A new student, the Antarctican Quetzalcoatl Sassassul, suddenly transfers into the girls' school one day, much to the intrigue of everyone in the class. But for some reason, Himeno seems to have experienced some sort of childhood trauma involving Antarcticans. The new student is as kind and friendly as can be, but Himeno just can't shake her fear... Meanwhile, everyone in the class has lots of questions for Sassassul...

On her way to school one morning, a boy from another school gives Himeno a love letter. The sudden turn of events has Himeno bewildered, and behind her bewilderment likes a traumatic memory from her childhood. What happened in Himeno's past? Himeno and Nozomi have come to Kyoko's house for a study meeting. As they're working, something strange happens...

Himeno has a young cousin named Shino-chan. Manami, as well, has three young triplet sisters, and an even younger fourth sister. One day, Manami orders her triplet sisters to stay home and watch their youngest sister while she goes out. This leads the four youngest Mitama sisters to experience a truly mysterious phenomenon...

Himeno has been featured in a fashion magazine! Could it be that she's working part-time as a model? Suspicion and wild ideas fill the minds of Nozomi and Kyoko, but what is the real story? Himeno's class visits a school for merfolk to participate in a joint class. The students of the two classes begin to build relationships as they interact throughout the day, but the highly unique merfolk students remain a source of intrigue.

As they read a script that Mitsuyo wrote, Kyoko and Nozomi have various criticisms... Just what is Mitsuyo's story about? All the girls in the class are holding an arm wrestling tournament. Who will be the victor? Even as the trepidation hangs in the air, the heated battle begins. Who will the goddess of victory smile upon in the end?

Sue-chan, the youngest of the Mitama family, has a weak constitution. Manami and her triplet sisters are always worrying about her. On the other hand, Himeno's niece, Shino-chan, isa very curious girl. She asks Himeno all kinds of questions as they go for a walk, and looks adorable doing it. All the little ones—Himeno's niece Shino-chan, as well as Manami's triplet sisters and baby sister Sue-chan—live their own stories.

Suu-chan the Antarctican is going on a date with a boy in her class. Himeno, Nozomi, and Kyoko are worried about her, so they quietly follow the couple... At the same time, Manami is on a date with a girl from her class, and they end up talking about her father...

It's nearly time for the school fair, and Himeno's class is putting on a play. Himeno is chosen to play the princess, and after much consideration, Nozomi is chosen to play the prince! With the guidance of the class president, Manami, preparations begin to come together. Then, when the curtain rises at last, the unexpected happens...Kyoko is completely exhausted in the middle of running a marathon for PE class. What will become of her?

A wasted Takato has spent the night with Ayagi. The next morning, Takato looks at his phone and sees that Junta had been trying to contact him all night…

While Hamazura is out running errands for Mugino, SCHOOL stages an attack on ITEM. When Mugino runs from Kakine, Takitsubo offers to protect Hamazura, but ends up needing his help instead. Kakine issues a challenge to Accelerator.

Tamaki finds herself in an art slump and can’t seem to shake it off. Sensing something is wrong, Ayame attempts to cheer her up.

Tamaki is confronted by a spirited girl. As a member of the Illustration Club, the girl challenges Tamaki to a duel among artists.

Kyo asks Tamaki for her help in writing some song lyrics. This leads Tamaki to believe that Kyo is in love and wishes to help.