Ayumu Ishikawa Retires After Final Season With Oosterhout Twins

Ayumu Ishikawa announced his retirement on Saturday, November 7, closing a career that stretched from a decorated 12-season run with the Chiba Lotte Marines to one final year with Oosterhout Twins in the Dutch Honkbal Hoofdklasse.

Oosterhout said the 38-year-old right-hander played a key role in club history, most notably when he led the Twins to their first Baseball Champions League Europe victory. His retirement comes less than two months after he said he hoped to continue playing in 2027, making the announcement a definitive change in plans.

Ishikawa’s European final chapter

Ishikawa joined Oosterhout for the 2026 season after leaving Chiba Lotte. He adapted to a different role and schedule in the Netherlands, working as both a starter and reliever while helping the Twins finish third in the Hoofdklasse.

• 2026 record: 5-2 in 15 appearances
• ERA: 2.89
• European highlight: Six innings of one-run baseball against Regensburg
• Result: Oosterhout’s first Baseball Champions League Europe win

That European breakthrough came on May 22 in Regensburg. Ishikawa allowed five hits and one earned run, walked two and struck out six over six innings as Oosterhout defeated the Guggenberger Legionäre 2-1. He left with the lead after 97 pitches, and the bullpen protected it to complete a landmark result for the Dutch club.

It was a fitting final-season highlight for a pitcher whose command and composure had defined his career. Ishikawa also contributed in the Dutch postseason, where Oosterhout’s campaign ended in the semifinals.

From NPB Rookie of the Year to Dutch baseball

Chiba Lotte selected Ishikawa in the first round of the 2013 NPB Draft. He won 10 games as a rookie in 2014 and received Pacific League Rookie of the Year honors.

His best season came in 2016, when he went 14-5 with a 2.16 ERA and won the Pacific League ERA title. Ishikawa finished his NPB career with a 79-66 record, a 3.49 ERA and 769 strikeouts across 1,211 innings. He made 197 appearances for the Marines and represented Japan at the 2017 World Baseball Classic.

Rather than immediately moving into coaching after leaving Lotte, Ishikawa chose an unconventional final chapter in Europe. He joined Oosterhout, experienced Dutch baseball and helped a regional club earn a place in European competition history.

His retirement ends a career remembered for high-level success in Japan and a final season that carried unusual international significance.