One of the many galaxies scattered across the universe: the Fioria Galaxy. A girl has just enlisted in the Fioria Galaxy Space Defense Force, the outfit that keeps this galaxy at peace. Her name is Lapiness Sapphire.

But on her very first day, luck turns on her — the Rogoru Pirates, space raiders who leave every neighboring world in ruins, ambush her ship. The attack sends the ship out of control, and a wormhole swallows it whole…

Lapiness wakes in the ship’s communications room. But something about her surroundings is off — she seems to have slipped out of the universe she knew and into another dimension. 　

To reach her own ship again, she has to press on through a looping accessway, making the right call every time. 　　

Inside the accessway: 　
・If there’s no anomaly, head for the blue door. 　
・If there is an anomaly, head for the red door. 　　

Pick the right door, and she draws closer to her own dimension and her way out of this wormhole. Pick the wrong one, and what awaits her is the vicious Rogoru Pirates…!