The six units are introduced at the Unknown Underground Unbelievable Ultimate Fes. (U4 Fes.), a mysterious music festival that takes place once every 100 years. Happy Around! receives its invitation in the mail, and although the four agree to participate, Rei notices the lack of a return address.

While Maho ponders what Happy Around! needs to improve on, Rinku suggests dancing. After the four attempt to follow popular dances and fail, Rinku proclaims dancing is about being passionate and creates an image of Africa with the unit dressed in animal costumes. Happy Around! emulates The Lion King with their dance, ending with Muni raising Nyochio.

Peaky P-key's popularity draws the media to them for interviews, which reaches the point where they interfere with the unit's practice and daily lives. With a concert approaching, Esora creates robot counterparts of the four that participate in the press functions while the actual girls practice. Shortly before the performance, the four notice the robots have been severely worn down and tearfully give their blessings as they go on stage.

Lyrical Lily was elegantly having afternoon tea in the Arisugawa Academy gardens... when Kurumi brings in a heap of snacks?!

"Wait, aren't we forgetting something?" Happy Around! had completely forgotten to register for the Legendary Fes. What do we do?!

What you need for DJing... muscles! What you need for performances... muscles! What you need to hype up the Fes.... muscles! A fierce battle is about to begin...

"Let's discuss how we can improve our singing voice!" The members Rinku called together brought with them items that helps their singing.

Muni Ohnaruto is guided by fate, and visits an unexplored land. What awaits her at the end of her journey...?

"What can I do to be considered the cutest in this school?!" To bring out the cuteness in Muni-chan! A super producer rises up! The name is... Nyochio!

Hey! Hey! Hey! The U4 FES. preliminaries has begun! Numerous trials are given to the chosen DJ units! Can Rinku and her friends pass the preliminaries?!

Maho is feeling inadequate again, "I think there's more we can do." Rei proposes trying new instruments. HapiAra's new possibility opens up! Or maybe not...?

A good rest is essential for the best performance! Kyoko sets out to town alone, without the other members. Little did she know that Peaky miracles awaited her...

Producer Shano gives Photon Maiden a day off. Towa proposes showing Saki around Tokyo. The four's bonds deepen through the sightseeing. Their bonds will surely take them to a new universe...!

Merm4id becomes stranded on a deserted island while on their way to a resort. In spite of their predicament, the four collect food with ease before assembling a raft. As they depart the island, they are swallowed by a whale before being shot out through its blowhole.

Rondo is celebrating a successful show with drinks at a rooftop restaurant when Hiiro asks the group if they have experienced something "sweet" recently, though they fail to provide good answers. After Aoi changes the restaurant's background music, the four picture performing the song and Hiiro realizes they were unable to find anything sweet as they already have the unit. Noticing Tsubaki's gaze and her ordering a drink called a Glad Eye, Hiiro points out the definition of a glad-eye, to her embarrassment.

Lyrical Lily is preparing to host a concert in a church when a blackout occurs. After lighting a candle lamp, Haruna attempts to console Miyu and investigate, both of which Miiko and Kurumi point out are common death tropes in horror films. Ghosts appear in the building, scaring Haruna and Miyu until Kurumi turns on the lights and reveals they are a product of her projection mapping as she feels an exorcism theme would fit their show.