BBK/BRNK

Kazuki Azuma returns to Japan after ten years away and is rescued by his childhood friend, Asabuki Kogane.

Believing that the heart Bubuki will react if its owner is in danger, Hiiragi attacks Azuma with Iwatooshi.

Azuma and his companions flee Shinjuku and meet a woman named Horino, who tells Azuma that his mother was the only person to ever defeat Reoko and her Buranki, Entei.

Kogane engages Matobai in battle but is soon overwhelmed, and when Azuma attempts to save her, the heart Bubuki finally awakens.

The Bubuki battle continues aboard the train that's carrying Oubu toward Treasure Island, and Hiiragi can't help wondering about the true nature of the relationship between Kinoa and Arabashiri.

Azuma's companions have won their second Bubuki battle, but their next opponent is someone who they didn't expect.