Tokyo, capital of Japan.

The mysterious man called Phantom, his dark forces has been sealed.He is trying to get back his darkness power behind the scenes.

Give armour called F.A (Fu-mantion Artifact) to young girls has supernatural powers, with deal that he grant them wishes, if they win a battle.

Because the hard strikes by F.A in a battle field will twist the space time and makes cracks toward shadowy world.
Eventually this cracks will unsealed Phantom's missing power.

The Kumon family protect the world against Phantom.
Waka is a daughter of Kumon and Mikoto stood up and join Waka to protect from Phantom's plot.
But he escaped and kidnap Waka's younger sister of Nagi.

Itsuki, the maid intend to be a hero.
Yuzuha, is a Ninja who escaped from Phantom's bait.
They also joined Waka and Mikoto.

Now, the four girls started chasing after Phantom to get back Nagi.