BBK/BRNK, also known as Bubuki/Buranki (ブブキ・ブランキ), is a Japanese anime television series created by Sanzigen to celebrate their 10th anniversary. It aired from January to March 2016.
A second season was announced at the end of the first season's final episode, subtitled The Gentle Giants of the Galaxy (星の巨人, Hoshi no Kyojin) it aired from October to December 2016.
Azuma Kazuki is a young boy living with his family on Treasure Island, a floating island several thousand feet above Earth that is inhabited by giant sentient robots called "Buranki", all of which are "sleeping". However, several of the Buranki are starting to wake up, forcing Migiwa Kazuki, his mother, to send Azuma, his sister Kaoruko, and their father down to Earth in a Buranki named Oubu for safety, leaving her behind.
Ten years later, Azuma, returning to a post-apocalyptic Shinjuku is captured by the authorities, but was saved by his childhood friend Kogane Asabuki, a user of a sentient weapon known as Bubuki, which also forms a Buranki's limbs. Discovering he is a Bubuki-user himself with the Heart of Oubu, Azuma and Kogane unite with three other Bubuki-users: Hiiragi Nono, Kinoa Ōgi and Shizuru Taneomi, to work together to seek and revive the lost Oubu, and discover the hidden truths behind the Buranki and the mysterious Reoko Banryū's tyranny over the post-apocalyptic Japan with her own Buranki: Entei.