After spending one year in the United States, Kurisu Makise returns to Akihabara and reconnects with Rintarou Okabe. Yet their reunion is abruptly interrupted when Okabe starts to see recurring glimpses of alternate timelines, the fallout from his time‑travel experiments. These side effects ultimately cause Okabe to disappear from existence, leaving only the shocked Kurisu with any recollection of him.
In the depths of despair, Kurisu confronts a daunting dilemma that tests her scientific duty and personal loyalty. She must decide whether to heed Okabe's warning and refrain from time‑traveling, thereby protecting the world lines, or to defy it in order to rescue the one she holds dear. Whichever choice she makes will ripple through past, present, and future. Her decision will shape the destiny of countless lives, forcing her to weigh personal affection against the fragile balance of time and the universe's fragile tapestry forever.