Despite their distinctive personalities, Souma Shiki, Hayate Ichikura, Shun Futami, and Takayuki Mima all have one thing in common: though naturally clumsy, the four disguise their embarrassment from tiny slip-ups by maintaining a composed demeanor. However, it is actually the guys' airheaded natures that makes the girls' hearts throb. No matter what happens in their daily lives, the boys do their best not to lose their cool!

A special unaired episode of Musaigen no Phantom World bundled with the series' seventh DVD/BD volume.

Sixth grader Sana Kurata has a perfect life. Her mother is a (fairly) successful author, she has a young man employed to keep her happy and safe, and best of all, she is the star of the children's television show Kodomo no Omocha. There's just one thing bothering her, and that's Akito Hayama. Akito is a classmate of Sana's, and ever since he's started acting out in class, the rest of the boys have followed his example. Every day, the girls and the teacher wage a battle to keep the class under control and to get some actual learning done. That rotten Akito… Sana won't stand for this! The hyperactive Sana decides to dig deeper and find out what makes Akito tick, so class can go back to normal and the teacher can stop spending every day crying instead of teaching. But the more she learns about him, the more she realizes that there might be more to Akito than meets the eye.

For the regular cells of the human body, life consists of countless repetitive tasks. They spend every day multiplying, leaving little time for other activities. But one day, this monotony is abruptly interrupted by a cell with an odd-looking hat. Tired of unending drudgery, another cell named Ippan Saibou decides to join this quirky stranger for a day of pranks, jokes, and mischief.