“ Desperate times call for extraordinary heroes... ”

Takamine Yuuto is a regular guy with a heavy responsibility. After losing his parents, instead of relying on relatives he decides to live independently and provide for his stepsister Kaori. Their life together is hard, but pleasant; passed in friendly quarrels with his rival Shun, and accompanied by their childhood friend Kyouko.

But the wheel of fate moves as it wills. In an astonishing turn of events, Yuuto and his sister are summoned to another dimension: the land of Phantasmagoria. Kaori is held captive, and without the ability to understand or communicate in this new world, Yuuto is compelled to become an Etranger - a warrior of power - and take up the sword, becoming a force in the conflict raging in this alien world.

To protect Kaori, the unwilling Yuuto throws himself into the fray. But as he fights alongside the fighters known as Spirits, living among the people of Phantasmagoria, he slowly comes to discover other reasons for his ongoing struggle...