Having vanquished the Demon Lord Garius, Akatsuki Ousawa bids farewell to the world of Alazyard and returns to his home world. He brings with him Miu, the busty daughter of the dark lord, who must pretend to be his long-lost sister. The two enroll at Babel, an academy for students with special powers, and find the adventures are just beginning.

Miu mourns her father's death and fends off Akatsuki's pervy advances. The two arrive for their first day at Babel Academy and find they're already the talk of the school. Miu hopes to fit in and make friends, while Akatsuki manages to make a few enemies right away.

Because of Akatsuki's antics, the student council has threatened to send Kuzuha back to elementary school unless she spies on him. Meanwhile, Onizuka hatches a plan to get back at Akatsuki.

Akatsuki conjures a new weapon and saves the day, but the battles aren't over. Meanwhile, Miu tries to process her father's final words.

Miu visits a shopping mall for the very first time to buy some new underwear. But hijinks ensue when Akatsuki gets a little more involved than he should...

Akatsuki attempts to ride the fabled Sleipnir motorcycle. Meanwhile, terrorists strike in the heart of the city, and it's up to the student council to stop them.

While Akatsuki and friends participate in a game of Beach Swimsuit Tag, powerful figures in Alayzard hatch a plan to find and retrieve Miu.

As the school-wide ranking battles begin, all eyes are focused on Akatsuki and Miu. Even Kyoya and the student council are eager to show Akatsuki who's boss!

After the BABEL ranking matches are suddenly thrown into chaos, Phil Burnett arrives from Alayzard to retrieve Miu.

The epic battle between Akatsuki and Phil Burnett continues. Meanwhile, Miu struggles with the notion that she's the cause of all the trouble in both worlds.

Having been outclassed by Akatsuki, Phil uses his trump card and transforms into a giant dragon! Akatsuki's friends and the student council members struggle to buy time until Akatsuki can fully recover from Phil's poison.

Akatsuki and Miu face off with Zahhak in a final battle. Meanwhile, the truth behind Phil is revealed in Alayzard, and COCOON takes further notice of Akatsuki.