Yugo Tennouji is a tall, muscular man with a bald head, beard, and sharp jawline, typically seen wearing a yellow shirt and a green apron emblazoned with "I Love CRT," signifying his deep passion for cathode-ray tube televisions. This passion, combined with owning the Braun Tube Workshop (or CRT Workshop), earned him the nickname "Mr. Braun" from his tenant Rintaro Okabe, referencing CRT inventor Ferdinand Braun. Despite an imposing and occasionally intimidating demeanor, he shows kindness and concern for those close to him, though he possesses a short temper easily triggered by disruptions like Okabe's experiments, often resulting in idle threats to raise rent. His daughter, Nae Tennouji, is his absolute priority, dictating his actions to ensure her safety and happiness, including adjusting shop hours around her school schedule. His background involves a harsh upbringing as an orphan in Paris sewers. Homeless, he encountered a gellified human, leading to his recruitment by SERN, which provided escape from poverty. Relocated to Akihabara, Japan, in 1997, he met neighbor and mentor Suzu Hashida, and Tsuzuri Imamiya, whom he married. After burning down his home to hinder SERN—disguised as a smoking accident—Suzu took him in; he eventually purchased the building housing his workshop and the Future Gadget Lab from her. He married Tsuzuri, and they had Nae. However, in 2001, while Tsuzuri was pregnant with their second child, SERN gellified her to coerce Yugo's continued loyalty. Before Okabe's involvement, operating under the codename "FB" (for Ferdinand Braun), he recruited Moeka Kiryu into SERN's covert Rounders group. He manipulated Moeka using a female online persona, exploiting her psychological needs to ensure obedience. In the original *Steins;Gate* narrative, Yugo appears as Okabe's stern landlord, frequently clashing over noise. He hires Suzuha Amane part-time due to their shared CRT interest. His hidden role as FB and SERN operative is later exposed by Okabe and Moeka. Confronted by Suzuha being the future daughter of Suzu Hashida—whose memory he felt he dishonored—and recognizing his expendability to SERN, Yugo chooses suicide. In the anime, he fatally shoots Moeka before taking his own life to protect Nae from SERN. In the *Steins;Gate 0* Beta world line, Yugo's SERN history persists, though his motivations shift. Despite initial Rounder affiliation, he allies with Okabe after Nae witnesses rival operatives. His goal becomes shielding Nae, leading him to shelter Kagari Shiina and Suzuha Amane by employing them. He uses interrogation skills to help Okabe identify threats against Kagari. In this timeline, Yugo never met Suzu Hashida (as Suzuha traveled to 2010 instead of 1975), resulting in a more ruthless personality less influenced by Suzu's redemptive impact. His devotion to Nae remains unchanged. Following convergence onto the Steins Gate world line, Yugo operates his shop peacefully, unaffiliated with SERN. He hires Moeka Kiryu part-time and continues to dote on Nae, as seen in later stories set in August 2019. His fluency in Japanese, English, and French, along with his technical expertise in CRT maintenance, are consistent.