BBK/BRNK

Kazuki Azuma returns to Japan after ten years away, only to be chased down by the Bubuki police. He's saved by a childhood friend, Asabuki Kogane, and her right-hand-shaped Bubuki. He then meets the Bubuki users Nono Hiiragi, Ougi Kinoa, and Taneomi Shizuru. Azuma has never even heard of Bubuki, but after learning that he's the user of the "heart" Bubuki, he makes his way to the Buranki prison in Shinjuku's underground to awaken the sleeping Buranki called Oubu.

Azuma stares in stunned shock at Oubu, now reduced to bones, as Hiiragi, Kogane, and the others successfully hold off Matobai. Hiiragi realizes this is the best chance to awaken Oubu and demands the heart Bubuki from Azuma, but Azuma insists he has no such thing. Believing that the heart Bubuki will react if its owner is in danger, he attacks Azuma with Iwatooshi!

Ten years ago, many Buranki fell to Earth and were destroyed by Banryuu Reoko and her Buranki, Entei. That was the day Reoko and Entei's reign of terror began. In the present, Azuma and his companions flee Shinjuku and meet a woman named Horino, who tells Azuma that his mother was the only person who ever defeated Reoko. She then tells him there's more he should know, and leads him to the "Kazuki library."