Steins;Gate

Kurisu has returned to Akihabara after a year in America, and although she and Okabe have a somewhat romantic reunion, their time together does not last long. Okabe begins to have images of other timelines, and ultimately disappears from everyone's sights and memories. Kurisu must fight against her own heart to decide whether to follow the path of a scientist and follow Okabe's words to not go back in time to get him back, or let her emotions drive her to save her most precious person, no matter what dangerous effects it may have on the world.