Sakura is a high school delinquent who, as a member of Bofurin, has vowed to “protect this town.”

Ren Kaji and the second-year senpai rush in to save Sakura and the others when a fierce attack is upon them.

Bofurin is able to defeat every member of Natori-led KEEL and safely rescue Nagato.

The battle with KEEL is now over, and one afternoon…Sakura doesn’t show up at school. Worried, Nirei contacts him and can tell over the phone that Sakura’s got a terrible cold. That day after school, Nirei and Suo, representing the first-year class 1, head to Sakura’s apartment with a care package. Sakura came from out of town, but what kind of life is he living now?

Sakura deeply feels that he wasn't able to do much during the battle with KEEL. When Sakura goes to Kaji to seek some advice, Kaji bluntly says, "You need to trust them based on what you have seen." In addition, Umemiya encourages him to "Jump right out there with everything you've got!" After recovering from his cold, Sakura enters the classroom determined. He faces Nirei, Suo, and the rest of the first-year class, and begins to share his honest thoughts about being grade captain…

Tsubakino leads Sakura, Nirei, and Suo to the home of an old man named Ito.

As a thank you for helping Ito recover, Tsubakino takes Sakura, Nirei, and Suo to the neon-lit entertainment district of “Keisei Street,” which is full of cozy drinking establishments, mahjong parlors, and bars. The boys are overwhelmed by the atmosphere of this part of town. They head to meet up with Tsubakino when suddenly, a girl in a tattered white dress falls on Sakura. They have no chance to hear the girl’s story before a group of thugs approaches them.

Sakura, Nirei, and Suo, having saved the girl chased by thugs whose name is Shizuka Narita, run into a suited team called Roppo Ichiza, led by someone named Kanji Nakamura. The Roppo Ichiza is a strong fighting team that had many clashes with Bofurin before the school was unified. However, there is no conflict between the two groups at present. The group goes to Burlesque Bar Ougi, where Kanji and Shizuka work, and see Tsubakino pole dance while his two lieutenants are sitting at a nearby table.

The name of the group pursuing Shizuka is GRAVEL, a group of delinquents from the Sunaba District, a notorious area known for its rough reputation. They begin to rampage through Keisei Street again, this time with more members, in an attempt to capture Shizuka. However, the members of Roppo Ichiza, Sakura, Nirei, and Suo are ready to confront them! Roppo Ichiza struggles in the fight due to the overwhelming number of GRAVEL forces despite them being beaten down one after another. Meanwhile, Tsubakino, Seiryu, and Uryu wait with Shizuka at the Burlesque Bar OUGI.

Unable to bear anyone getting hurt because of her, Shizuka attempts to run to Shuhei Suzuri, the leader of GRAVEL, while ignoring the calls from Nirei and the others. However, she is stopped by Tsubakino, Seiryu, and Uryu. Tsubakino asks what she wants to do, to which Shizuka responds, “I want to stay with everyone!” This prompts Tsubakino to finally show the seriousness of the Four Kings. Tsubakino asks what Suzuri likes and gradually, their fists become part of a conversation, as the battle between Tsubakino and Suzuri continues.

“All of us will work together and become one unit.” Suzuri-led GRAVEL resolves to walk a different path “together” as they take the extended hand of Roppo Ichiza. Shizuka, whose decision would have made everyone sad, sincerely apologizes and expresses her gratitude to Tsubakino and Kanji. Just then, as they have reconciled and everyone’s feelings are in sync, a former Furin student named Endo, covered in tattoos from his back to his shoulders and arms, appears.

Sakura, Nirei, and Suo are called up to the roof of Furin High School. Waiting for them are the Four Kings, their next-in-commands, and Sugishita, who’s helping Umemiya. Having heard about the recent events from Tsubakino, Umemiya has called everyone here to tell the story of Endo, who was the mastermind behind the conflicts between KEEL and GRAVEL, and to explain the origins of the Bofurin unification. As Umemiya, Hiragi, Tsubakino, Momose, and Mizuki join Furin High School and become a part of the Bofurin; what shadow is born as a result of this?