Tatsuya Yoigoshi is a first-year student at Noukin High School. He was once a famous junior high school soccer ace, celebrated under the moniker "Unbeatable Yoigoshi" for his exceptional talent as a striker. Upon entering high school, however, he developed a deep-seated aversion to sports and cut all ties with them, shifting his focus to a new identity as an online livestreamer named Night End, broadcasting in headphones and a mask.

Despite his rejection of athletics, he found himself persistently recruited by various school teams, refusing every offer—until members of the school’s kabaddi club, including Souma Azemichi, approached him. Scoffing at the invitation at first, he was eventually persuaded to observe a practice. There, the vice-captain, Kei Iura, challenged him to a one-on-one match against Azemichi: if Yoigoshi won, he could leave; if he lost, he would join the club. After his defeat, he reluctantly honored the agreement and became a member.

He has silver-gray hair and vermilion eyes. As part of the Noukin Kabaddi Club, he wears a red uniform and jersey number 6.

His demeanor is surly and arrogant, marked by a temper that flares easily but can also subside quickly. This volatility showed in his early resistance to the team, particularly during defensive drills that required forming chains with teammates—he refused at first, insisting on practicing as a raider despite an initial success rate of zero.

A personal detail remains his fondness for fried chicken, which is his favorite food.