Book 1

Heart Gear, Vol. 1

by Tsuyoshi Takaki

Published 15 August 2023
In a postapocalyptic future, a human girl and an android travel the world in search of a mythical utopia to protect those they love.

Nearly 200 years after the destruction of humanity in World War III, Roue lives a happy life exploring the ruins of civilization with her “uncle,” a robot named Zett. But when their peaceful life is threatened, Roue must trust the mysterious robot Chrome to bring her family together again.

After Roue accidentally activates Chrome without a base program—what is essentially a robot’s soul—she and Uncle Zett invite him into their makeshift family and encourage him to choose his own purpose. But when an insane machine attacks their home, will Chrome survive, much less find his purpose?

Book 2

Heart Gear, Vol. 2

by Tsuyoshi Takaki

Published 21 November 2023
In a postapocalyptic future, a human girl and an android travel the world in search of a mythical utopia to protect those they love.

Nearly 200 years after the destruction of humanity in World War III, Roue lives a happy life exploring the ruins of civilization with her “uncle,” a robot named Zett. But when their peaceful life is threatened, Roue must trust the mysterious robot Chrome to bring her family together again.

Following the advice of new friends, Roue and Chrome set off to find Heaven Land, a gear utopia, in order to revive Uncle Zett. But when a threatening gear blocks their path, Chrome unknowingly takes on a vicious combat form that frightens Roue. What other secrets might Chrome have that he doesn’t even know himself? And when their next lead on Heaven Land brings them to Valhalla, a coliseum of warriors, what horrors will Chrome unleash when he’s forced to fight once more?

Book 3

Heart Gear, Vol. 3

by Tsuyoshi Takaki

Published 20 February 2024
In a postapocalyptic future, a human girl and an android travel the world in search of a mythical utopia to protect those they love.

Nearly 200 years after the destruction of humanity in World War III, Roue lives a happy life exploring the ruins of civilization with her “uncle,” a robot named Zett. But when their peaceful life is threatened, Roue must trust the mysterious robot Chrome to bring her family together again.

Hildr, a command-class military gear, has just won 50 back-to-back fights inside the warrior coliseum of Valhalla and now faces her 51st opponent—Chrome. As the two face off, Roue is forced to watch helplessly from the confines of a storage room on the lower levels. But while both Chrome’s and Roue’s attention is focused on the battle at hand, Valhalla’s ruler begins to hatch his own sinister scheme. Unbeknownst to her, Roue holds the fate of Valhalla in her hands, and danger is creeping ever closer!

Book 4

Heart Gear, Vol. 4

by Tsuyoshi Takaki

Published 21 May 2024
In a postapocalyptic future, a human girl and an android travel the world in search of a mythical utopia to protect those they love.

Nearly 200 years after the destruction of humanity in World War III, Roue lives a happy life exploring the ruins of civilization with her “uncle,” a robot named Zett. But when their peaceful life is threatened, Roue must trust the mysterious robot Chrome to bring her family together again.

General Wodan has been waiting centuries for the one thing he needs to make his dreams of the ultimate command a reality—a human biosignature. And now that Roue has fallen into his lap, he’s able to rewrite the base program of every gear in Valhalla and force them to fight according to his will. The general has declared war, and Chrome must emerge victorious to have any hope of saving Roue before it’s too late!

Book 5

Heart Gear, Vol. 5

by Tsuyoshi Takaki

Published 17 June 2025
In a postapocalyptic future, a human girl and an android travel the world in search of a mythical utopia to protect those they love.

Nearly 200 years after the destruction of humanity in World War III, Roue lives a happy life exploring the ruins of civilization with her “uncle,” a robot named Zett. But when their peaceful life is threatened, Roue must trust the mysterious robot Chrome to bring her family together again.

Roue continues her journey to Heaven Land under the protection of Chrome and Rock, but her very existence has put Heaven Land in a difficult position. Unable to reach an agreement, they dispatch two teams to intercept the girl—the Donkeys, who they’ve assigned to welcome her, and the Elephants, who have been ordered to eliminate them all. Now the race is on to find out which group will decide Roue’s fate!