After a year in America, Kurisu Makise returns to Akihabara and reunites with Rintarou Okabe. However, their reunion is cut short when Okabe begins to experience recurring flashes of other timelines as the consequences of his time traveling start to manifest. These side effects eventually culminate in Okabe suddenly vanishing from the world, and only the startled Kurisu has any memory of his existence. In the midst o...