The early parts of an anticipated season have come with struggles at the plate for the Seattle Mariners.

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Their upcoming four-game series against the Houston Astros’ banged-up pitching staff could offer a reprieve, but the series opener also presents a unique challenge.

The Mariners are set to see a pitch they never have before on Friday night when they face Japanese right-hander Tatsuya Imai and his viral “wrong-way slider” for the first time.

What exactly is a “wrong-way slider?” Well, it’s a unique pitch that does exactly as the name indicates: breaks in the opposite direction of a traditional slider. Imai is able to generate this movement by getting his pitching hand under the slider when he releases. You can get a look at one of the nastiest ones Imai has thrown in his first two MLB starts in the clip below.

Tatsuya Imai’s Wrong Way Slider. 🤪

13 inches arm side run. pic.twitter.com/sFYc1Hm1tQ

— Rob Friedman (@PitchingNinja) April 4, 2026

Imai’s slider is averaging nearly 6 inches of arm-side break, per Baseball Savant. The average MLB slider has 4 inches of glove-side break, so Imai’s slider has a 10-inch difference in break in the opposite direction of a traditional slider. The movement is more in line with the horizontal break of a traditional changeup or split-finger – Imai throws both of those, too – and could easily be mistaken for the basically extinct screwball.

According to Baseball Savant, just 11 MLB pitchers are averaging arm-side break on their sliders this season. Imai’s has the most at more than three times greater than next-closest pitcher.

Imai struggled in his first MLB outing, but he bounced back against the Athletics on Sunday with nine strikeouts over 5 2/3 scoreless innings.

A’s veteran Jeff McNeil, who struck out on one of Imai’s sliders, spoke about what it was like seeing the pitch for the first time postgame.

“It was kind of doing everything,” McNeil said via MLB.com’s David Adler. “Some went left. Some went right. It was pretty interesting to see. You don’t see a lot of pitches like that.”

The Mariners should see quite a bit of Imai’s unique slider Friday. He’s thrown it 41.7% of the time, second to only his 46.4% usage of his four-seam fastball. The pitch has generated a 44.4% whiff rate and batters are hitting .222 (4 for 18) with eight strikeouts against it.

A former NPB star in Japan, Imai signed a three-year, $54 million deal with Houston during the offseason.

Mariners-Astros pitching probables

• Friday: Mariners right-hander Emerson Hancock (1-1 record, 0.71 ERA) vs. right-hander Tatsuya Imai (1-0, 4.32)
• Saturday: Mariners right-hander Luis Castillo (0-0, 2.79) vs Astros right-hander Lance McCullers (1-0, 3.27)
• Sunday: Mariners right-hander Logan Gilbert (0-2, 5.40) vs TBD
• Monday: Mariners right-hander George Kirby (1-2, 3.60) vs TBD