There are 4 Japanese MLB players played for the Oakland Athletics

Hideki
Okajima

LHP Boston Red Sox

(Boston Red Sox , Oakland Athletics, Yomiuri Giants, Hokkaido Nippon Ham Fighters, Fukuoka SoftBank Hawks, Yokohama DeNA BayStars)

岡島秀樹 (おかじま・ひでき)

Bats: L Throws: L

Current Age 45

6-1, 195lb (185cm, 88kg)

MLB Debut:
2007-04-02 (31)

Akinori
Iwamura

2B/3B Tampa Bay Rays

(Tampa Bay Rays, Pittsburgh Pirates, Oakland Athletics, Tokyo Yakult Swallows, Tohoku Rakuten Golden Eagles)

岩村明憲 (いわむら・あきのり)

Bats: L Throws: R

Current Age 42

5-9, 200lb (175cm, 90kg)

MLB Debut:
2007-04-02 (28)

Keiichi
Yabu

RHP Oakland Athletics

(Oakland Athletics, San Francisco Giants, Hanshin Tigers, Tohoku Rakuten Golden Eagles)

藪恵壹 (やぶ・けいいち)

Bats: R Throws: R

Current Age 52

6-0, 200lb (183cm, 90kg)

MLB Debut:
2005-04-09 (36)

Hideki
Matsui

LF/DH New York Yankees

(New York Yankees, Los Angeles Angels, Oakland Athletics, Tampa Bay Rays, Yomiuri Giants)

松井秀喜 (まつい・ひでき)

Bats: L Throws: R

Current Age 47

6-2, 210lb (188cm, 95kg)

MLB Debut:
2003-03-31 (28)