It's a time of warfare where relentless battles continue between human and demi-human tribes like the Ash Monkeys (Macaque) and pig people (Ogres) invading human lands. Kai, a boy from the village of Rag, spends his days immersed in battle to protect his village. Amidst the harsh battles enforced by those possessing immense power known as "guardian bearers," and as his comrades fall one by one, Kai suddenly recalls memories he shouldn't have experienced—memories of a world with advanced technology and knowledge of people's lives beyond this world. And thus, although Kai was just a villager, he soon finds himself embroiled in great trials... A magnificent fantasy tale unfolds, chronicling the struggle and growth of a single boy in a harsh world.

Thunder and fire kill people, rumors spread, and rat-faced sinister soldiers rampage across the imperial capital. Everything seems to point to the secrets of the former dynasty that were wiped out by thunder and fire. A pair of hands brought three very different young men together. Jing Yifei, the cold and proud female master of Jinwu Guard, was ordered to find out the truth about the rat soldiers. Bai Qi, the descendant of Jieyi who lives in seclusion in the mountains, led his master to go down the mountain to find a young machine master to join the Jinwu Guard. But the person he was looking for, Qin Ming, was deceiving and abducting him!? As the three of them continued to work together, they gradually came closer to the truth about Lei Huo. (Source: iq.com)

After the decline of the once robust fields of science and technology, a new energy source known as magic fuels the modern era. Humanity creates forbidden biological weapons: Gears. Those Gears eventually stand against humanity in a rebellion. Although they manage to overcome in the struggle for survival known as the Crusades, humanity's losses are so great that even after several decades pass, their emotional wounds remain unable to fully heal. Sin Kiske, the child of a human and a Gear, heads to his father Ky and mother Dizzy's wedding ceremony. Their wedding breaks the ultimate taboo: a union between a human and a Gear. Even with the world at peace, it took many years for such a ceremony to come to fruition. Despite the complex array of emotions surrounding it, the wedding ceremony is met with blessings. When suddenly, a mysterious girl appears... The fated child inheriting Gear blood–and the mysterious girl who despises Gears. Their meeting would shake the world.

Fourth season of .