Episode: Steins;Gate - 16 - Sacrificial Necrosis 3k5p

Unable to get much information about the badge maker's client, Rintaro decides to leap back in time to confront the client in question, only to find it was Daru, who wanted to make a fake badge to cheer Suzuha up. Daru then reveals that Suzuha's time machine is only able to travel backwards in time, meaning they won't be able to see her again once she leaves. As the repairs to the time machine are completed, Mayuri deduces from the time machine's name that Suzuha's father is actually Daru. After a short reunion, Suzuha travels back to 1975, though Rintaro notices the Divergence Meter's reading has not changed. A few hours later, Yuugo delivers a letter written by Suzuha in the year 2000, revealing that she had committed suicide a year later. In the letter, Suzuha laments that she had failed her mission, as the damages to the time machine caused her to crash and lose her memories for 24 years. Blaming himself for stopping Suzuha on the night of the storm that damaged the time machine, Rintaro sends a D-Mail that stops him from following Suzuha, letting her use the time machine before it was damaged. Speaking with Yuugo again in the new World Line, Rintaro learns that Suzuha had died of illness instead and receives her Divergence Meter, which is now showing a different value.

Source: Wikipedia