Step into a tale of parallel universes...

Iris was born in World DE-1, a world that mirrors Earth in the 2000s. With her birth, a series of tragic loops was set in motion, which were gradually unraveled by the efforts of Arata Mizunashi and his team.

With her goodwill restored, Iris created a copy of World DE-1 named World DE-1.5. Here, feuds gave way to friendship, each person a perfect cog in a perfect world. But a new crisis threatens the peace...

A mysterious man has entered the fray, and he leads a group of people who look identical to the world's former heroes. Our new hero, Sayaka Hiwatari, confronts the rising chaos, where friends and foes seem impossible to distinguish.

And so the battle with another world enters a new phase...

[From Steam]