Tennomifune Academy is an elite institution for the best and the brightest, with the exception of Class 1-7, the so-called Happiness Class. Each member of the classroom copes with personal misfortunes, and the special class is geared to help them move past their issues and find true happiness. After being accepted into the academy, An Hanakoizumi, Ruri Hibarigaoka, and Botan Kumegawa find themselves placed into the Happiness Class, plagued by dreadful luck, love problems, and bad health respectively. Alongside their classmates, they do their best to overcome the difficulties they are faced with in pursuit of a life filled with joy.

Kohane Hatoya’s most lovable trait is also her greatest flaw. She loves to help others no matter how far she has to go in order to get the job done. Her biggest inspiration to do so comes to light when she sees what cheerleading looks like for the first time in middle school. Now a highschooler but as enthusiastic as ever, Kohane wants nothing more than to start her very own cheerleading squad. She's encouraged by her best friend, Uki Sawatari, who often has to help her get out of trouble. There is just one problem: Kohane does not have any experience in cheerleading. She has absolutely no idea what to do, what to wear, or how to perform. To make matters worse, she has been scared of heights since childhood, and this new sport is full of stunts pulled far from the ground for a girl her size. Enter Hizume Arima, a former cheerleader who wishes to leave her pastime behind. Unfortunately for her, Kohane recognizes Hizume, and will stop at nothing just so she can lead the new squad, even if it means facing her childhood fear.

Originally from a big city, Futaba Ooki spends most days cataloguing her life through pictures on her phone. Upon moving to a seaside town, she gazes out over the vast expanse of sea and quickly becomes captivated by its endless possibilities. Unbeknownst to Futaba, her quiet contemplation catches the attention of local diving enthusiast Hikari Kohinata. Finding herself in the same class as Futaba the next day, Hikari is drawn to her quiet and shy demeanor and affectionately nicknames her Teko, sparking a tender friendship. Struggling to adapt to the change of pace in her life, Futaba finds herself strung along by Hikari's vast energy and passion for diving. Together, they join the school diving club, led by their homeroom teacher Mato Katori. With Hikari by her side, Futaba works to earn her diving certification while experiencing new friendships and possibilities.

While testing out his camera on a bridge one summer night, Kaito Kirishima sees a blue light streaking across the sky, only to be blown off the railing seconds later. Just before succumbing to unconsciousness, a hand reaches down to grab ahold of his own. Dazed and confused, Kaito wakes up the next morning wondering how he ended up back in his own room with no apparent injuries or any recollection of the night before. As he proceeds with his normal school life, Kaito and his friends discuss what to do with his camera, finally deciding to make a film with it over their upcoming summer break. Noticing that Kaito has an interest in the new upperclassmen Ichika Takatsuki, his friend Tetsurou Ishigaki decides to invite her, as well as her friend Remon Yamano, to join them in their movie project. In what becomes one of the most entertaining and exciting summers of their lives, Kaito and his friends find that their time spent together is not just about creating a film, but something much more meaningful that will force them to confront their true feelings and each other.