Setsu was once summoned into the alternate world of Eclair, where he ended a war between humans, beastmen, and demons, and brought peace to the land. He was hailed as the hero who achieved world peace surpassing all racial barriers for the very first time, but after the war, he was sent back to his original world. Though he had to restart as a baby, he retained all his memories and powers from the other world.

Then, when he made it back to high school age, he was once again summoned to Eclair, where five years had passed and war threatened the land again...

[Source: Crunchyroll]

In 2030, people in Japan are turning into different forms of monsters based on their age, sex and race. The illness is named ‘Gibia’ - after being rich in variety like gibier. A pair of samurai and ninja appear in the blighted wasteland of Japan. They both traveled from the early Edo period, fighting together with help from a doctor who tries to find a cure for Gibia. Facing ceaseless attacks from Gibia, and outlaws that attack travelers for food, they start the dangerous journey with enemies all around.

[Source: Crunchyroll]

Oyone, who moved into a group home for senior citizens, forms a band with the other elderly residents. She relives the memories of her youth through a concert on Christmas night.

[Source: Anime News Network]