Tanji Washijō coaches the Shiratorizawa Academy boys' volleyball team. A native of Miyagi Prefecture who speaks in its regional dialect, his own high school volleyball career was thwarted by his short stature. This experience shaped his coaching philosophy, firmly believing height and natural power are essential for victory. For decades at Shiratorizawa, he recruited physically imposing athletes, emphasizing straightforward, powerful plays under the principle "simple is best," deliberately avoiding complex tactics. His strict discipline and intense vocal presence during matches earned him the nickname "Demon Coach." He openly criticizes players for errors, harshly reprimanding Tsutomu Goshiki for failed receives. He maintains distance during timeouts to foster player independence, though he privately acknowledges effort, like instructing players to "do a hundred serves" after Shiratorizawa's loss to Karasuno as tacit recognition. His player relationships are pragmatic: he rejected Tobio Kageyama for not fitting the power-centric style, while valuing Wakatoshi Ushijima as the ideal embodiment. Washijō initially dismissed Shōyō Hinata due to height, excluding him from a first-year training camp. However, he permitted Hinata to stay as a ball boy, privately respecting his perseverance despite publicly belittling him. During the camp, Washijō observed Hinata's progress but refused open acknowledgment, telling colleagues Hinata's "hunger to succeed" mirrored his own past struggles. His ideology shifted witnessing Hinata's performance against Kamomedai at Nationals. Seeing Hinata execute a minus-tempo attack, Washijō acknowledged players without height could compete through ingenuity and skill, realizing his lifelong focus on power stemmed from jealousy of taller athletes. This introspection led him to admit, "I didn't need to tell Hinata he was worthless without Kageyama." Post-timeskip, Washijō actively supported Hinata's development, connecting him with a beach volleyball coach in Brazil. He explained this assistance stemmed from high expectations, stating, "No one expects more from Shōyō Hinata than I do." Years later, he attended Hinata's professional V-League match, showing visible excitement at his growth. He remains Shiratorizawa's head coach and maintains ties with former players like Ushijima.