Episode: Steins;Gate - 15 - Missing Link Necrosis 3p1r3t

Suzuha explains how SERN was able to build a time machine and use it to create a totalitarian world in 2036, stating that she had originally planned to travel to 1975 to acquire an IBN 5100, but made a detour to the year 2010 to look for her father. When she tries to start the time machine, she discovers it has broken down, which Rintaro realizes was a result of the storm on the night he stopped her from leaving. Leaping to two days before the completion of the time leap machine, Rintaro gathers the lab to inform them of the situation. While Daru is tasked with fixing Suzuha's time machine, Mayuri suggests that everyone also help Suzuha find her father, using a pin badge he gave her as a clue. Suzuha also gives Rintaro a device called the Divergence Meter, which keeps track of the magnitude of differences between World Lines, and tells him about how he founded the resistance against SERN in the future. After spending the day searching for Suzuha's father, Rintaro is thanked by Suzuha before receiving a lead on Suzuha's father from a badge maker.

Source: Wikipedia