Iteris is a planet orbiting within the Aris system around 20 light years away from Earth. Because Iteris is so close to its star, it is always day on one half of the planet and night on the other half. The twilight strip passes along the meridian of the planet, the most fertile part of Iteris. The rich resources of this part of the planet caused the beginning of the Internal War between the Ora race, the inhabitants of the day side, and the Ombra race, the representatives of the night side.

You choose what side of the story you want to play first. The two main characters Leto (Ora) and Qell (Ombra) represent either sides. The stories intersect after some time when the characters meet and go together revealing the mysteries of the planet, the two races and the war. As a result you learn about the story from two points of view.

There are up to 6 endings in each chapter. All your in-game actions will impact the story and affect the change in character personality. You can build any kind of relationships with any characters depending on your choices.
Keep in mind that the two races have no genders differences unlike humans. Their age differ from human age due to different biology.

The main objective is to find a way to stop the war and unite people.