Nae Tennōji, born November 9, 1998, is the only daughter of Yugo Tennōji and Tsuzuri Imamiya. Her mother died during childbirth, leaving her to be raised solely by Yugo in their small apartment above his CRT TV repair shop in Akihabara. Exhibiting a timid and reserved personality during her 2010 childhood, she is often frightened by Rintaro Okabe's "Hououin Kyouma" persona and his nickname assignments, though she forms close bonds with Mayuri Shiina and Suzuha Amane, viewing them as older sisters. Occasionally, she adopts a strict alter ego called "Sergeant Clean," mirroring her father's authoritative demeanor during cleaning. Her life endures significant trauma across world lines. In one Alpha world line, she accidentally causes Mayuri's death by pushing her in front of a train during a SERN pursuit while attempting a hug, leaving Nae severely traumatized. In the 0.523307% divergence world line (explored in *Steins;Gate 0*), she witnesses her father's suicide and blames Okabe and Moeka Kiryu for his death. This drives her to join SERN's Rounders in the future. By 2025, she captures, tortures, and kills Okabe, then uses SERN's confiscated time-leap machine to travel back over 2,000 times to 2010 seeking revenge. She murders Moeka and injures Okabe, stating she has "nothing left" in her original timeline and implying she might repeat her vengeful cycle indefinitely. The anime adaptation alters this event, depicting Yugo's suicide at a construction site without Nae present, suggesting she avoids this path in that continuity. In the *Linear Bounded Phenogram* side story (set in the 0.337161α world line), Yugo's suicide recurs. Nae becomes adopted by Faris Nyannyan's family. Two years later, as a middle schooler, she struggles with unresolved grief and fixates on time travel theories. She encounters Daru in an arcade and collaborates with him to rebuild the Phonewave (name subject to change), sneaking into the abandoned lab and assisting with component acquisition despite SERN agent surveillance. This period highlights her resourcefulness and lingering trauma as she navigates guilt over lying to Faris while pursuing a connection to her past. By 2019–2020 (*Robotics;Notes*), now 20, she relocates to Tanegashima and works for JAXA. She supports the Robotics Research Club financially and logistically, aiding their goal to build a robot for the Tokyo Expo. Despite an outwardly cheerful and energetic demeanor, her eyes often lack warmth, noted as "not smiling" by observers. She demonstrates exceptional combat skills, incapacitating SERN militants and leading assaults on their facilities. Her expertise in fighting games earns her the alias "Flat-Out Princess" in Akihabara. She briefly dates Kaito Yashio but rejects him, believing he sees her as a substitute. Her unresolved emotional state persists, reflecting the lasting impact of her father's death and experiences across world lines.