Seiryū Kotajima

Honestly, Seiryū Kotajima might be my favorite kind of baseball story — the late bloomer who shows up and immediately makes everyone look silly for sleeping on him. A sixth-round pick out of Chuo Gakuin University, nobody outside Orix circles knew his name in early 2024, and then he went out and posted a 0.79 ERA across 50 relief appearances while setting an NPB rookie record with 22 straight scoreless outings. That's not a fluke, that's a guy who simply figured something out. And the emotional fist-pumps on the mound? Completely infectious. He wears every out on his face, which I find way more entertaining than the stone-cold closer act. Kid lost his father in early 2025 and became a dad himself the same year he debuted — carrying all of that while transitioning to a starting role takes a different kind of toughness. I'm watching this one closely.

Seiryū Kotajima is a Japanese professional baseball player born on June 29, 1999, in Kawachi-machi, Ibaraki Prefecture, Japan. He attended Ibaraki Prefectural Toride Shoyo High School before going on to study at Chuo Gakuin University. Personal details such as his agency and debut remain undisclosed or unknown.

Name (English)

Seiryū Kotajima

Name (Japanese)

古田島成龍

Reading

こたじま せいりゅう

Born

June 29, 1999 (age 27)

Zodiac / Chinese zodiac

Cancer / Rabbit (卯)

Origin

Kawachi-machi, Ibaraki Prefecture, Japan

Occupation

Professional Baseball Player

High school

Ibaraki Prefectural Toride Shoyo High School

University

Chuo Gakuin University

Motto

Private

• Instagramhttps://www.instagram.com/kotajimaseiryu/
• Wikipedia (Japanese)https://ja.wikipedia.org/wiki/%E5%8F%A4%E7%94%B0%E5%B3%B6%E6%88%90%E9%BE%8D

Tags

• From Ibaraki Prefecture
• Professional Baseball Player

Last updated

2026-06-02

Facts are limited to publicly available information up to 2024; non-public or unconfirmed items are omitted. English text is machine-assisted (facts translated by Sonnet, "My Take" written by Opus 4.8). The Japanese page is the source of record.