Build-Divide -#000000- Code Black

Hiyori pleads to become Teruto's disciple, and follows Teruto and Sakura around; Teruto is pulled into a crowd of protestors and gets separated from Sakura and Hiyori; a young man named Naomitsu Enjo appears and helps Teruto.

Teruto now has eight chips in his possession after claiming victory against Naomitsu. Sakura goes to meet Teruto so they can find Rebuild Battle challengers. When she gets there, she discovers that Hiyori has asked Teruto to give her special Build-Divide training. Teruto refuses at first, but reluctantly accepts after Hiyori entices him with his favorite foods. The three head toward the school store and make an unexpected discovery. Meanwhile, a girl asks Ishinome to take her to Teruto. Ishinome agrees knowing that something interesting may happen and sets a trap to lure Teruto. What is the girl’s objective?

Teruto loses his steam after being defeated by Kikka and spends his time in a daze, fishing by the river. He doesn’t have the drive to win like he did before, not only because he lost to Kikka who is his younger sister, but because he also found out that she is now the King of Neo Kyoto. Kikka longs to battle Teruto again because it is the only thing that excites her. However her attendant, Higuma, does not allow her to go outside, because he says that she must rest in order to prepare for a big event. Teruto refuses to listen to Sakura or Hiyori’s advice, and goes out alone but a man appears in front of him and…?

At Kamitoba Beach Resort, Teruto meets Ai Utsurogi from the bakery, who turns out to be a childhood acquaintance of his; when he visits AI's bakery, she tells Teruto about her memories of him and Kikka during their childhood.

After regaining all of his memories, Teruto focuses on taking part in Rebuild Battles so that he can reach Kikka as soon as possible. When he is one card away from completing the key, a boy in elementary school named Mikhail Saiki challenges him to a match. Mikhail is a formidable opponent who is also only one card away from challenging the King. However, Mikhail is surprised to see Hiyori with Teruto. Mikhail realizes that Hiyori is the kind girl that helped him the other day. What will be the outcome of Teruto’s final battle to complete his key?

Sakura challenges the King; she challenges Kikka to regain her own body; unable to take part in Rebuild Battles on her own, she tricks Teruto into fighting the battles that are needed to complete the key and appear before the King.