Sequel of Bubuki Buranki.

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.

The year is 2032, seven years after the Second Great Kanto Earthquake decimated Tokyo. Now, the city is reborn as MegaTokyo, built from the labors of mechanical beasts known as Boomers. Originally created to benefit humanity, the mysterious corporation known as Genom now produces Boomers with incredible destructive power as a new type of advanced weaponry, capable of disguising themselves as humans. The AD Police is a new special unit to counter the ever-increasing Boomer-related crimes. Overwhelmed by the sheer amount of crimes and disparity in strength, the AD Police poses little opposition to the Boomers. A mysterious vigilante force known as the Knight Sabers, wearing powersuits more advanced than the military, is the citizens' only hope for protection. Led by Sylia Stingray, Priscilla Priss Asagiri, Nene Romanova, and Linna Yamazaki, these beautiful girls take out any Boomer that steps out of line.

When ordinary high school student Aoba Watase is suddenly targeted by a giant robot known as a Valiancer, he is saved by his mysterious classmate Hina Yumihara. After revealing that she and their robotic enemy are from the future, Hina suddenly propels Aoba 70 years forward in order to prevent his death. Upon arrival, Aoba finds himself in the cockpit of a Valiancer called Luxon, stuck in the midst of a firefight between the military forces of the Free Pact Alliance (FPA) and Zogilia Republic. After he shows high compatibility with an FPA pilot named Dio Weinberg, the two perform a successful coupling, allowing them to share experiences and subsequently increase their capabilities and skills. Although Aoba is able to survive this unexpected battle, he is taken into custody by the FPA ship Cygnus, who wishes to interrogate him. While the student's main concern is whether he will ever be able to return home, what he doesn't realize is that he is about to get caught up in a war to protect the world.