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After saving a fairy-tale kingdom, Akatsuki returns to the real world with his prize--Miu, the busty daughter of the Demon King. It's one hell of a happy ending until they're force to enroll at a school for magic users.

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?—MAL Rewrite

Known as a Rogue Hero in the fantasy world Arezard, Akatsuki decided to take upon the request of the defeated Demon King to take his daughter with him. After bringing her back to the world he came from, Akatsuki brought her to join Babel, an academy-like organization that specializes in training those who came from the other world.—Anime News Network

Hero defeats bad guy. Good triumphs over evil. The end. Or, at least that's how it usually goes. But what happens after the hero goes home? Ohtorizawa Akatsuki, is about to find out that sometimes the greatest adventure starts after the happy ending.—Crunchyroll

Magic kingdom saved. Dark Lord defeated. His daughter successfully snuck through isekai customs. Akatsuki's story is over, right? Wrong. Back in the real world, magic school is mandatory, classmates are devious, and oh-he and Miu have to act like siblings.—Funimation