Mets starting pitcher Kodai Senga, of Japan, throws during the...

Mets starting pitcher Kodai Senga, of Japan, throws during the first inning of a spring training baseball game against the Washington Nationals, Thursday, March 16, 2023, in West Palm Beach, Fla.  Credit: AP/Lynne Sladky

PORT ST. LUCIE, Fla. — When Kodai Senga’s first stateside spring training was interrupted this month by tendinitis in his right index finger, a minor pain caused at least partially by the grip of his signature splitter on a slightly different American baseball, manager Buck Showalter knew just whom to call: Koji Uehara.

Uehara stopped into Mets camp Wednesday at Showalter’s request and — in addition to catching up with his former Baltimore manager — discussed with Senga their shared experience.

Yes, Uehara told Senga, part of the transition from baseball in Japan to the majors in the United States for him was the literal baseball. And yes, the splitter — integral to the success of both righthanders — specifically required an adjustment period. But no, related issues did not last.

“He said it’s no big deal, so I shouldn’t be worried about it,” Senga said through an interpreter Sunday. “That was reassuring.”

Showalter echoed: “[Uehara] said he had it a little bit early but went away. I think that was comforting for Kodai to hear. Right now he doesn’t feel anything, so we’re hoping that adjustment has been made.”

In his outings since a brief mid-camp break, Senga has refrained from throwing his splitter — branded as the “ghost fork,” a nickname Senga did not invent but does embrace — almost entirely. Last year, Senga estimated, he threw it one-quarter of the time.

Showalter said Senga will try it out again in his final preseason start, which will be an intrasquad scrimmage at Clover Park on Monday, the Mets’ last day of spring training.

Between Uehara and that imminent finale, Senga had an additional highlight: a visit from Daisuke Matsuzaka, another Japanese hurler who knows all about making the jump to the majors as a highly hyped phenom with a mysterious trademark pitch (remember the alleged gyroball?).

Senga described Matsuzaka as a childhood “role model,” an icon in Nippon Professional Baseball whose dominance inspired Senga to mimic his mechanics and slow windup. When Matsuzaka joined the Red Sox for the 2007 season, Senga was 14. By the time Matsuzaka played for the Mets in 2013-14, Senga had begun his professional career. When Matsuzaka returned to Japan to play more seasons thereafter, he joined the Fukuoka Softbank Hawks — Senga’s club.

A November/December tour of major-league cities and clubs ended with Senga deciding on the Mets. When he signed, Matsuzaka reached out with a message, Senga said: “You picked a really good team.”

“I actually played with him on my old team back in Japan for a little bit, so I had some conversations with him back then,” Senga said. “It was good to catch up and hear some stories and whatnot to see what it’s like over here.”

Soon, Senga will know a lot better what it’s like over here. He is scheduled to start the Mets’ fourth game of the season — Sunday in Miami — and make his Citi Field debut April 8, also against the Marlins.

Although Senga got into only three Grapefruit League games, Showalter has been pleased with his work. Senga described the past two months as “pretty good” because he had “no big setbacks or injuries.”

“If you would’ve told me coming in that he’d be where he is, I’d have been very happy with it,’’ Showalter said. “He’s like a sponge. We try to give him as much [help and information] as he might need from different avenues. He’s the one that’s leading that charge a lot. He’s very inquisitive.

“I’ll tell you one thing, he’s very competitive. Any concerns I might’ve had about his adjustment, I don’t have as many as I had.”

Senga said early in spring training that he was actively enjoying his time in Port St. Lucie, a sentiment that is not particularly common among players. But now he is ready for the real thing.

“I just want to make it a good day,” he said of his looming debut. “Obviously, it’s my first step into the big leagues and first step into something that I’ve always dreamt of. I just want to make it a good day and something memorable.”

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