Steins;Gate - episode 14 - 05 Jul, 2011

As Okabe makes several time leaps in an attempt to protect Mayuri, each one ending in failure, who learns that the lab was targeted by SERN due to their creation of a time machine and their plan to publicly announce it. Falling into despair over his repeated failures, Okabe is approached by Kurisu, who gets him to reveal his situation and gives him key trigger phases to get her past self to cooperate with him. After being sent to just before the time leap machine's completion and obtaining Kurisu's aid, Okabe is approached by Suzuha, who explains that in order to save Mayuri, they need to escape the "Alpha World Line Attractor Field," where Mayuri is doomed to die, due to the converging nature of world lines, and cross the 1% Divergence point to the Beta World Line Attractor Field, where the outcome might possibly be different. Suzuha then takes Okabe and Kurisu to the crashed satellite, which turns out to be a time machine, and reveals she is in fact "John Titor" and has come from the year 2036. (Source: Wikipedia)