Nae Tennouji

The only daughter of Yuugo Tennouji and Tsuzuri Imamiya, Nae is a young girl living in fear of Hououin Kyouma.

Personality
A very timid and reserved girl, Nae likes to keep out of Okabe's way, as his Hououin Kyouma persona frightens her. She is good friends with Mayuri and Suzuha though and thinks of them as her older sisters, often exchanging a friendly "Tutturu" with Mayuri, and hanging around with Suzuha when she is working in the CRT TV store.

She loves her father very much and often feels like she's imposing on him, even going so far as to learn cookery from Mayuri and Kurisu for his sake.

Plot
(SPOILER ALERT)

Vengeful Nae
In World Line Divergence 0.523307% (0.337187% in the anime), Nae witnesses her father commit suicide. Traumatized by this event and with nowhere else to turn, she joins SERN's rounders. Calculating her plan of vengeance against those that "killed daddy", she works her way up in the ranks and becomes a commanding officer during the Dystopia. Finally, after 15 years of waiting she captures Okabe in the year 2025, torturing him without mercy until he dies. After this she takes the Time Leap Machine, makes thousands of leaps until she arrives in the year 2010, there she executes the second part of her plan, killing Moeka. After stabbing Moeka through the heart, she cuts a large gash into Okabe's arm and tells him to wait in fear for his inevitable death in 15 years.

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, pushing Mayuri in front of a speeding train and killing her. Nae is traumatised by this event and it's unknown what happens to her. Unlike in World Line Divergence 0.337187%, Nae's actions here seem to be unintentional.

Trivia

 * In Robotics;Notes, which lies in the same universe as Steins;Gate, Nae returns as a 20-year-old employee of JAXA.