Shuichiro Oishi holds the vice-captaincy of the Seishun Academy tennis club and forms one half of the nationally renowned "Golden Pair" doubles team with Eiji Kikumaru. Their partnership combines Oishi's strategic stability with Kikumaru's agility and unpredictability. On court, Oishi displays a calm, rational demeanor, enabling swift tactical shifts. Off court, he frequently exhibits concern for the team's welfare, earning him the "Mother Hen of Seigaku" nickname. Despite this anxious persona, his leadership in team management and matches reveals a disciplined, strict approach. His playing style emphasizes net control and tactical lobs, featuring signature moves like the "Moon Volley", a high-arcing topspin lob designed for precision landings, and the "Drop Volley", disguising a drop shot with volley power. The Golden Pair utilizes coordinated formations: the "Australian Formation" (positioning centrally to obscure intent) and the "I-Formation" (Kikumaru crouching net during Oishi's serves). Their synergy evolves into "Oishi Territory", focusing on Oishi's net play and court-reading while directing Kikumaru's baseline coverage, achieving "Synchronization" – moving as a unified entity. Beyond doubles, Oishi engages in team-building and comedic segments, including a recurring family-themed parody where he assumes a maternal role. His disciplined nature manifests in meticulous attention to etiquette and team protocols. Later, Oishi earns the No. 16 position as a first-string player for Japan’s U-17 training camp, becoming one of 14 selected middle schoolers representing Japan internationally. During the U-17 World Cup, he undertakes the responsibility of drawing tournament placement lots for the entire Japanese team, signifying his trusted role within the squad.