When a massive solar simulator explodes in the sky, the world is plunged into permanent darkness for over 500 years. This event is known as the "Eclipse." In this new age of darkness, humanity steps into a world dominated by advanced technology and artificial intelligence. However, this growing technology, while connecting people, also becomes increasingly dangerous.

The protagonist, 17-year-old Kira, is an AI engineer and begins investigating the mysterious explosion behind the Eclipse. Her findings lead her to face one of the world’s most powerful AI entities, Aether, which aims to reshape society with its superior intelligence.