Moonlight Parker thinks she lives in a normal world, unaware of the magic that runs in her blood. Minu Ginger is the victim of a tragic past, in which a war took both her parents.

When Moonlight gets a visit from Minu —her newly assigned unicorn— she’s introduced to a world she’s never imagined. Harmony is a magical place in the clouds where unicorns, dragons, and magical beings called Petunians live alike, unknown to humankind.

Minu is the ruler of Harmony and has now introduced Moonlight to the future she will lead at Manona High, a school of magic in the clouds. Moonlight is to study the magic in her blood at Manona High, and she learns how to control the powers within her Strixcus —the relic she uses to perform magic.

But it all goes downhill when Minu reveals to Moonlight her dark past, and the brother she used to have. Guller Ginger is the monster who struck a war against the rest of Harmony.

He rallied up all Dark Unicorns —the bloody creatures who are the only enemies known to Harmony— in an attempt to take over Harmony, and murder his own sister. When bodies start dropping dead at Manona High, Moonlight can’t take it anymore.

The abnormal magic, the dead bodies, and the murderer out to get her and her friends are too much for her. But when Guller reveals his return, hell reigns glory over the surface of the clouds, and it's obvious that he’s coming for Moonlight —the only Maroon Petunian alive other than Guller himself.

The hunt for the Noble Ruby begins, and now Moonlight has to stay and fight. It's a race against time, magic, and Guller himself.

Bodies drop dead, betrayal is in the air, and history is bound to repeat itself. .