Kōshū

Biodata

Feature	Details
Name	Kōshū (高之野)
Alias(es)	“Seven Innings Ace” 394
Gender	Male
Nationality	Chinese-born Japanese 80
Affiliation	Kinoshita Little League; Japan U15 National Team; Seido High School Baseball Club
Occupation/Role	Student; right-handed pitcher and batter; Seido’s ace pitcher; occasional left fielder 161 398
Status	Active
First Appearance	Chapter 1

Pitching Development

Benchmark	Chapter	Notes
Approx. 120 km/h	6	Corrected his throwing mechanics by driving from his back leg through his fingertips; his control became safe enough to work all four corners.
Over 140 km/h; over 136 km/h average	77	A growth spurt to 1.88 m and a longer stride moved his release point forward, increasing the force of his Straight Ball.
145 km/h	131	Reached 145 km/h after four months of Seido training.
Around 146 km/h	205	Reported that his velocity had plateaued and sought greater lower-body strength to break through it.
149 km/h	294	Threw 149 km/h against Kyoma University; his usual Straight Ball average was noted as around 143 km/h.
150 km/h	316	Reached 150 km/h by the Hakuryu match.
152 km/h	386	Threw a 152 km/h pitch during Seido’s game against Inajitsu.

Background / History

Kōshū’s early life was unsettled. He overheard his parents discussing an impending departure and arguing over who would care for him, an experience that contributed to his detached outlook 1. After joining the Sasaki household, he attended language school while living at home, having already taught himself the language; he maintained solitary morning runs as a way to clear his mind 2.

Four months later, he transferred to Magnolia Middle School and entered the same grade as Lang Zhi despite being a year older 4. He began baseball in his second year of middle school and adapted unusually quickly to technical instruction because his body could immediately reproduce movements once he understood them 6 369.

At Kinoshita Little League, Kōshū developed from a beginner into the team’s ace. Senior Nozawa’s advice helped him overcome his initial difficulty fitting in and become a more accepting teammate 279. He led Kinoshita to the Summer Tournament championship by pitching the entire final, then earned the U15 World Cup’s Best Winning Percentage Pitcher award after helping Japan finish among the world’s top three 77 84.

Appearance

Kōshū is an exceptionally tall, lean athlete whose rapid growth has repeatedly affected his play. He was recorded at 193 cm and 78 kg, and is a right-handed pitcher and batter 398.

• Reached 1.88 m during middle school, when his weight decreased despite increasing strength 77.
• Reached 190 cm by the Autumn Tournament period 205.
• His teammates associate his intimidating game-face with his growing presence as an ace; he began shaving regularly as he matured 73.
• His height and athletic build led Sawamura to nickname him “Mount Everest-kun” during their first meeting 91.

Personality

Kōshū initially presents himself as quiet, withdrawn, and difficult to read. He spent his early time at Kinoshita as a “wallflower,” speaking little unless directly addressed 7. He is highly observant, quickly notices technical details in games, and is able to understand what others prefer or expect from him 15 173.

He is a perfectionist who carefully maintains the image of a strong, dependable pitcher. As teammates increasingly rely on him, he finds that image restrictive and struggles to openly show anxiety, fatigue, or frustration 173 215. His stability nevertheless becomes one of his defining strengths at Seido, where Kataoka considers him unusually reliable among the team’s pitchers 131.

Kōshū also possesses a strong competitive aggression. He recognizes baseball as an acceptable outlet for his desire to overwhelm opponents, particularly when pitching under pressure 152. Over time, he learns to restrain that impulse when team strategy demands it, prioritizing victory over personal satisfaction 240. He is more playful around Lang Zhi and can be bluntly critical of people he sees as careless or unwilling to acknowledge others’ effort 77 380.

Abilities & Skills

Pitching Repertoire

Kōshū combines velocity, command, pitch movement, and a broad arsenal.

• Four-Seam Fastball / Straight Ball — His primary weapon; its speed, spin, and command make it difficult for batters to time 87 103.
• High-Spin and Low-Spin Straight Balls — Uses changes in spin and rhythm to disrupt timing 87.
• Two-Seam Fastball — Adds movement to his fastball-based approach 87.
• Cutter / Fast Cutter — Used alongside his Slider to strike out elite opponents, including Harada 159.
• Slider — A high-velocity breaking ball visually close to the high 130 km/h range, with substantial movement despite its speed 370.
• Straight Ball-type Changeups — Changes batter timing without abandoning his fastball-like release 87.
• His workload is monitored because of shoulder concerns; Kataoka limits his innings to protect him 370.

Command and Pitching Strategy

Kōshū’s control is one of his most recognized strengths.

• Demonstrated command of the nine-section target grid under Miyuki’s direction 87.
• Can execute plans through sharp inside pitches and slower outside pitches, changing both location and timing within an at-bat 183.
• Took over pitch-calling during the Red and White Game when the first-year catcher needed guidance 97.
• Thinks tactically under pressure, such as entering against Kyoma University with the explicit aim of forcing a double play 181.
• His tendency to shoulder responsibility alone can push him toward overexertion or concealment of injuries 152 255.

Flow State and the Zone

Kōshū can enter states of extreme concentration during both pitching and batting.

• Entered a Flow State against Yakushi, including an Inside Corner Ball that stunned Todoroki Raichi; he completed a perfect game against Yakushi’s lineup 147.
• Experienced a brief breakthrough while batting against Ichidai, feeling his body and mind synchronize as though he had glimpsed the level of elite hitters 276.
• Entered “the zone” against Hongo at Spring Koshien and hit Hongo’s first pitch for a home run 324.
• He cannot consistently sustain the batting sensation after reaching it, and feels a sharp loss when it fades 276.

Batting

Although primarily a pitcher, Kōshū develops into a major offensive threat.

• Became part of Seido’s cleanup group, surpassing regular first baseman Maezono in recent batting data 203.
• Improved his lower-body strength and adjusted stance gave him a Spring Koshien batting average above .400 324.
• Won all four matchups with Narumiya Mei in their Inajitsu game, including hitting a home run in their direct confrontation 243 255.
• Hit home runs off Hongo and against Ichidai Third during the Spring Tournament 324 376.
• Growth spurts initially destabilized his batting motion despite strengthening his pitching 77.

Speed and Fielding

Kōshū’s sprinting background gives him uncommon mobility for a pitcher.

• Recorded average base-to-base running speed below four seconds during Little League testing 39.
• Revealed himself as a national-level sprinter by stealing both second and third base in a Koshien game 183.
• His base-running aggression can create scoring chances, but it also increases fatigue and injury risk for a pitcher 183.
• Played left field when Seido’s pitching rotation required it; his laser-like throw was memorable enough for Hakuryu’s Mima Soichiro to recall it later 134 316.

Health and Workload

• Secretly planned to have his shoulder examined after leaving the bullpen early; he did not want his condition to affect team morale 205.
• Was restricted from team fielding practice and trained in the Equipment Training Room while separated from the on-field group 209.
• Concealed an ankle injury after the Inajitsu match; an X-ray confirmed a slight strain and soft-tissue contusion requiring rest 255.
• His foot was fully recovered by the following finals, allowing him to start on the mound again 269.
• Seido’s staff secretly monitored his diet and health after he vomited on the mound during Summer Koshien 350.

Relationships

• Lang Zhi / Sasaki Rōchi — His younger brother. Kōshū teases, trains, and sometimes pressures Lang Zhi, but the two consistently support one another through baseball and family issues 15 42 80.
• Miyuki Kazuya — Primary catcher, strategist, and frequent source of tension. Their tactical understanding drives Seido’s strongest performances, though Miyuki is also concerned by Kōshū’s tendency to overextend himself 147 152 240.
• Nozawa — Former Kinoshita ace and mentor. His advice helped Kōshū understand the mindset required of an ace and later helped him integrate into the Little League team 28 279.
• Hayakawa Aki — Early mentor at Kinoshita and captain of the U15 team. Hayakawa helped Kōshū learn baseball fundamentals and supported his integration into Japan’s national squad 15 80.
• Kataoka Tesshin — Seido’s manager. He trusts Kōshū in decisive situations but holds him accountable for hiding injuries and carefully protects his shoulder workload 181 255 370.
• Sawamura Eijun and Furuya Satoru — Fellow Seido pitchers and rivals for the ace role. Their rivalry begins with the “Anti-Kōshū Alliance” and evolves into mutual pressure to improve 94 217 366.
• Narumiya Mei — Elite rival who first showed Kōshū the gap between ordinary pitchers and a true ace. Kōshū later defeats him in four direct showdowns, earning Narumiya’s recognition 25 255.
• Hongo Masamune — A fellow ace and “destined rival.” They exchange letters about goals and training while preparing for future confrontations 294 398.
• Okumura Koushuu — First-year catcher whom Kōshū mentors, teaching him how to safely receive his varied pitches 355.

Story Role / Major Arcs

Kinoshita Little League

• Learns pitching mechanics under Fujii and quickly raises his velocity to around 120 km/h 6.
• Becomes Kinoshita’s ace, confronting pressure for the first time in the rematch against Eimei Little League 63.
• Leads Kinoshita to the Summer Tournament championship by throwing the complete final 77.
• Starts for Japan against Chinese Taipei at the U15 World Cup, pitches a 12–0 shutout, and briefly speaks Mandarin with the opposing players 80.

Arrival at Seido

• Joins Seido as a freshman pitcher after entering from Kinoshita Little League 90.
• Displays his complete early repertoire and command test for Kataoka and Miyuki, then begins Spring Break with the Second String 87.
• Earns promotion to the First String after the Red and White Game and establishes himself through stable performances in the Kanto Tournament and training camp 131.
• Makes his high-school tournament debut during a bases-loaded crisis against Yokohama Kohoku 101.

Summer Tournament and Koshien

• Is initially assigned to left field during Seido’s Summer Tournament opener, reflecting the team’s rotation strategy 134.
• Pitches a perfect game against Yakushi, defeating Todoroki Raichi in their key duel 147.
• Helps Seido advance to Koshien by striking out Harada and challenging Narumiya Mei in the regional final 159.
• Becomes Seido’s de facto ace during Koshien, posting an ERA of 0 over more than ten innings as his assigned innings steadily increase 176.
• Replaces Tanba early against Kyoma University and immediately assumes the burden of leading Seido’s defense 181.

Seido’s Ace

• Is retrospectively described as having been appointed ace in the Autumn of his first year, despite senior pitchers remaining on the roster 369.
• Faces pressure from Sawamura and Furuya as both pursue the ace role, forcing him to reconsider what it means to accept challengers 225.
• Defeats Inajitsu and Narumiya Mei, but jeopardizes his place by concealing an ankle injury afterward 255.
• Returns from injury, continues to lead Seido at Spring Koshien, and develops into both a 150 km/h pitcher and a middle-order hitter 269 316 324.
• Is considered as a possible future captain after Seido’s third-years graduate 350.
• States his intention to pursue professional baseball while documenting short- and long-term goals in an interview 394.

Notable Quotes

“How about we beat them?” 320

“Isn’t that great?” 366

Trivia

• Kōshū speaks Mandarin, though he feels disconnected from both his Japanese teammates and the Chinese Taipei players he meets at the U15 World Cup 80.
• He exchanges shōjo manga with Isashiki, one of the Seido seniors he becomes closest to 145.
• He is notably careful about preserving his pitching form and has professional aspirations, which influences his approach to training volume 366.