Yuugo Tennouji

Yuugo is loud, intimidating and quick to anger, particularly when Okabe damages the building, neglects rent or mocks his devotion to CRT technology. His physical presence makes his threats considerably more convincing than Okabe's theatrical responses.

Around Nae, his demeanor changes completely. He is an affectionate single father who is fiercely protective of his daughter, and she is clearly the most important person in his everyday life.

Yuugo also has a history he rarely discusses. His gruff stability in 2010 conceals experiences involving poverty, violence and people who profoundly shaped his earlier life.

Yuugo has no supernatural abilities. He is physically strong and capable of intimidating most of the younger characters without needing a weapon.

His hidden work with the Rounders gives him experience with firearms, covert operations and SERN's command structure. He operates as FB, directing agents without normally meeting them in person.

His practical knowledge of CRT televisions also becomes unexpectedly useful to the Future Gadget Laboratory because the PhoneWave's time-travel effect depends on the large CRT downstairs being switched on.

Yuugo initially appears as the landlord whose Braun Tube Workshop occupies the ground floor beneath the Future Gadget Laboratory. His CRT television inadvertently becomes part of the conditions necessary for the PhoneWave's miniature black-hole phenomena.

Suzuha later works in his shop, giving Yuugo another connection to the laboratory's increasingly complicated activities.

Yuugo is eventually revealed to be FB, the Rounder handler directing Moeka and other agents for SERN. He was recruited into the organization when young and remained trapped within it even after building a life with Nae.

Okabe and Moeka track him while trying to recover the IBN 5100 and undo Moeka's D-Mail. In the original visual novel's Alpha-world-line sequence, Yuugo kills Moeka and then himself after being confronted; the anime adapts the confrontation differently in some details.

Nae Tennouji is Yuugo's daughter and the person he loves most. His desire to protect her strongly affects his decisions.

Suzuha Amane works for Yuugo at the Braun Tube Workshop. Their relationship is friendly despite his normally abrasive temperament.

Rintarou Okabe rents the upstairs room from Yuugo and constantly tests his patience through unpaid expenses, experiments and the nickname "Mr. Braun."

Moeka Kiryuu receives orders from Yuugo under his concealed identity as FB.

Tsuzuri Imamiya is Nae's mother and Yuugo's wife in material exploring his earlier life.