夏日心跳

The world has fallen into despair after being devastated by a poisonous substance called "shinobi," which arrived on Earth via an asteroid. Humanity has retreated to a place known as "Kairiku," once the ocean floor, where they struggle to survive against the poison’s effects. Amid this bleak existence, a single hope remains: the legendary "Holy Weapon Giga Road" and the warrior "Yagyuu," said to be the key to overcoming the poison. To save the world, Ame, a princess of a ruined nation, rises to fight.