As humanity's war with the Neuroi—a mysterious, hostile alien race possessing weapons of unparalleled power—continues being fought across Europe and Africa, a new fighter squadron is formed. The 502nd Joint Fighter Wing, also known as the Brave Witches, operates on the eastern front, scouring the icy vastness of Orussia in search of alien invaders. However, one of the Brave Witches' members suffers severe injuries on her way to the squadron's headquarters, rendering her unable to participate in any operations. As a result, her sister, Hikari Karibuchi, volunteers to take her place. Though not possessing any special abilities or significant magical powers, she is determined to live up to the expectations of her new comrades and prove herself worthy of the name of a Witch. [Written by MAL Rewrite]

Ryouta Sakamoto is unemployed and lives with his mother, his only real achievement being that he is Japan's top player of the popular online video game Btooom! However, his peaceful life is about to change when he finds himself stranded on an island in the middle of nowhere, with a small green crystal embedded in his left hand and no memory of how he got there. To his shock, someone has decided to recreate the game he is so fond of in real life, with the stakes being life or death. Armed with a bag full of unique bombs known as "BIM," the players are tasked with killing seven of their fellow participants and taking their green crystals in order to return home. Initially condemning any form of violence, Ryouta is forced to fight when he realizes that many of the other players are not as welcoming as they may seem. Teaming up with Himiko, a fellow Btooom! player, they attempt to get off of the island together, coming closer and closer to the truth behind this contest of death. [Written by MAL Rewrite]

Away from home for 10 years, Azuma Kazuki had no idea what was awaiting him upon his return. He certainly did not expect to be attacked by dozens of heavily armed people and taken as their prisoner. Fortunately, Azuma's stay in captivity is short. Wielding a strange sentient weapon—known as "Bubuki"—upon her right arm, his childhood friend, Kogane Asabuki, rescues him. After escaping, Azuma learns that he too has the power to control Bubuki. Together with his new companions, he must revive the Buranki titan named Oubu, that sleeps somewhere deep underground. With this knowledge and purpose, a new path to unearth the truths behind the Buranki opens before Azuma. [Written by MAL Rewrite]

Sequel of Bubuki Buranki.