Tokoshie × Bullet - Shin Minato Koubou-Sen

In this story, unidentified giant weapons will destroy the world's metropolises in 2029. The masterminds of this unprecedented destruction are known as "Tokoshie". They call themselves weapons when they go out on the streets of the cities with their overwhelming powers and disappear as soon as they are done with them. A decade has passed since then. A certain military company is developing a combat drone with the ability to fight the Tokoshie, and a certain millionaire figure goes underground to discover the secret of the Tokoshie's eternal life. Another specific girl goes on a journey to fight the Tokoshie, sworn in as her parents' enemies. In short, this is the chronicle of an endless struggle between humanity and its greatest enemy ever.