An extended version of the second season's first episode, which is under the same title.

In a futuristic world, young Marty stumbles upon a bionic arm which endows him with superhuman powers and put him at the centre of a centuries-old struggle between good and evil. His teenager heart will now begin a long-way training together with two loyal friends: Buttons, his robo-puppy, and the brave Ally. (Source: Official website)

Sasahara Natsuki is a poor bounty hunter in a world where monsters and humans live together. Most of her cases involve monsters infringing upon the rights of humans, who are protected by law from their generally more powerful neighbors. Being half-human and half cat-beast, Natsuki straddles the two societies and tries to understand and respect both while enforcing the law. She is assisted by a werewolf named Batanen who is afraid to admit he loves her; another werewolf named Tommy; and a Kyubi fox demon named Sakura who has her own plans--which include eating Natsuki to complete her her nine tails and thereby her magical powers.

Since the discovery of "Samon Syndrome" 30 years ago, thousands of young people have traveled to fantasy worlds, the few returnees managing to keep the special abilities they acquired in those parallel universes. Akatsuki Ousawa, known as the "Rogue Hero," discards his peaceful life in the fantasy world Alayzard to face new challenges upon returning to Earth. He comes back with Miu, the daughter of the Demon King he defeated, and is now forced to hide her true identity by having her pose as his little sister. The two soon join Babel, a special school designed for those who have acquired special abilities and magical powers through their journey to a fantasy world. Babel was seemingly founded to train young interdimensional travelers and "guide them to the right path for the sake of humanity and themselves," but its true purpose remains unclear to the pseudo-siblings. Will Akatsuki and Miu be able to overcome the hostile, powerful student council and uncover the forces at play behind the scenes? [Written by MAL Rewrite]