Nae Tennouji/Plot

Mayuri's Killer, Nae
In an unspecified Alpha World Line, Okabe and Mayuri attempt to flee SERN's attack by using the subways before SERN shuts them down. However, Nae follows them and attempts to hug Mayuri after catching up to her on the platform. However, she trips, leading to her accidently pushing Mayuri in front of a speeding train and killing her. Nae is traumatized by this event and it is unknown what happens to her.

Vengeful Nae
In World Line Divergence 0.523307% in the visual novel, Kurisu noticed Nae running away after her father's suicide, which implied that Nae had witnessed the event. Okabe, Kurisu and Moeka went to the latter's apartment to cancel the next D-Mail, but before Okabe could send it, Nae showed up at the apartment to kill Moeka and warn Okabe that she would kill him in 15 years. If the player chose to delay the D-Mail, Okabe decides to time-leap to before his confrontation with Yugo, and he instead stages it so that he can chase Nae and interrogate her about her cryptic warning. As Okabe realizes that Nae had time-leaped from 2025, she stabs him in his elbow and gradually jabs fingers in his wound during their conversation.

Traumatized by her father's suicide, she blamed the incident on Moeka for not stopping Yugo, and Okabe for, essentially, finding the IBN in this world-line. She joined the Rounders at some point in time, and brutally tortured and killed Okabe in 2025. Using the Future Gadget Lab's time-leap machine that SERN had locked up for 15 years, she time leaped over 2000 times, possibly double, to reach 2010 and exact her revenge against those who "killed daddy".

When Okabe asks how she will re-live the next 15 years, Nae tells him that "There's nothing for me there...", then proceeds to search for Moeka. Okabe later speculates that she would simply repeat her time-leaping and act of vengeance until she would lose sight of why she was time-leaping in the first place.

It is notable that the anime shows a different set of events for the same world line. Yugo takes Okabe, Moeka and Kurisu to an empty construction lot, so Nae does not directly witness her father's suicide and presumably does not go down a similar path of vengeance like in the visual novel.

The short manga side story Steins;Gate Rebellion of the Missing Ring - World Line 0.000000 also depicts vengeful Nae in 2025 in the worldline at 0% divergence.