Tadashi Shiroyama coaches Nankatsu SC and the U-13 Japan national team, first rising to prominence during the Kids' Dream arc. He steers Nankatsu SC to victory in the 6th Yomiuri Land Elementary School Tournament by appointing Tsubasa Ozora as captain after Genzo Wakabayashi’s injury. Later, he secures another championship in the 8th tournament with Shun Nitta leading the team post-Tsubasa’s departure. During the Boys' Fight arc, he mentors Tsubasa even after the latter leaves Nankatsu SC, offering tactical insights into Nitta’s strengths. His enduring impact spans five generations of players at the club, reflecting his sustained influence. On the international stage, he guides the U-13 Japan team through the U-13 International Tournament and The Great European Showdown. As captain, Tsubasa helps clinch a quarterfinal win over England (3–2), a semifinal triumph against France (2–1), and a draw in the final versus West Germany (2–2). Shiroyama’s strategic prowess further shines in the Europa Daikessen, where Japan defeats the All Europe Jr. squad 3–2. Known for adaptive leadership, he shifts captaincy based on team dynamics and partners with national supervisor Munemasa Katagiri during global competitions. His focus remains strictly on coaching, with no documented personal history or external interactions beyond his professional role.