Rintaro Sasaki Signs With Marlins: Japan’s Prep HR King Skips NPB for MLB

Rintaro Sasaki, the Japanese slugger who set his home country’s all-time high school home run record before crossing the Pacific to play at Stanford, is officially headed to professional baseball in the United States. The Miami Marlins selected the first baseman in the 2026 MLB Draft, and Sasaki has signed on — bypassing Japan’s top pro league entirely to chase a big league dream.

Key Takeaways

• The Marlins drafted Sasaki in the eighth round, 235th overall, in the 2026 MLB Draft.
• Sasaki hit 140 home runs in high school in Japan, a national record, then spent two years at Stanford.
• He is the son of Hiroshi Sasaki, the Hanamaki Higashi coach who developed Shohei Ohtani and Yusei Kikuchi.
• He turned down a first-round pick from Japan’s Fukuoka SoftBank Hawks in the October 2025 NPB draft to stay on the U.S. track.
• Over two Stanford seasons he batted .265 with 23 home runs and 88 RBIs in 106 games, an .872 OPS.
• Miami projects him as a power-hitting first baseman/DH who will begin his climb in the low minors.

An Unusual Path: From a Japanese High School Straight to U.S. College Ball

Sasaki’s route to pro baseball is one almost no Japanese player has taken. Most of Japan’s top amateur talents sign with a Nippon Professional Baseball (NPB) club — the country’s major league — straight out of high school. Sasaki did the opposite.

After finishing his high school career at Hanamaki Higashi — the same storied program that produced two-way superstar Shohei Ohtani and MLB pitcher Yusei Kikuchi — with a Japanese record 140 home runs, he declined to enter the NPB draft and instead enrolled at Stanford University in California. The connection runs even deeper: his father, Hiroshi Sasaki, is Hanamaki Higashi’s longtime head coach, the man who mentored both Ohtani and Kikuchi. That decision put Rintaro on a college track that eventually led to the MLB Draft, a pipeline rarely traveled by players who grew up in Japan.

Drafted in the Eighth Round, 235th Overall

Miami selected Sasaki in the eighth round of the 2026 MLB Draft, held in July, with the 235th overall pick. Scouts pointed to the raw power and refined swing he showed against tougher competition at Stanford as the traits that earned him a spot on a big league organization’s draft board.

Why He Chose America Over NPB — Twice

Sasaki had every reason to stay in Japan. When he skipped the NPB draft out of high school, he did so because he wanted to test himself in the American baseball environment as early as possible.

He doubled down on that choice even after arriving stateside. In Japan’s NPB draft in October 2025, the Fukuoka SoftBank Hawks (Pacific League, based in Fukuoka and one of NPB’s premier franchises) used a first-round pick on him, securing exclusive negotiating rights. Sasaki passed on the offer.

He could have returned to Stanford to build his résumé further, too. Instead, he concluded that entering a big league farm system now — and grinding through the demands of minor league life on the way up — gave him the best shot to develop. That reasoning drove his decision to sign.

Why Miami Bet on Sasaki’s Power

The Marlins have made adding thump to their lineup a priority, and Sasaki fits the need. Miami has leaned into acquiring power bats throughout its system to lift its home run and slugging numbers, with a particular eye toward stocking first base and designated hitter with hitters who can drive in runs. A slugger who has crushed the ball since high school checked that box.

What He Showed at Stanford

Across two seasons at Stanford, Sasaki appeared in 106 games and hit .265 with 23 home runs, 88 RBIs and an .872 OPS. Just as telling was his trajectory: he jumped from seven home runs as a freshman to 16 as a sophomore, a sign he was adjusting and his power was playing up.

That adjustment mattered. Like Japanese high school ball, U.S. college baseball is played with metal (BBCOR aluminum) bats, so Sasaki has yet to face the wood bats that define the pro game — a transition still ahead of him. Even so, against the faster velocity and sharper breaking pitches of American college arms, he proved his power translated. Questions remain about his speed and defense, but strong underlying data such as exit velocity and contact quality helped push him onto Miami’s board.

The Road to the Majors

Signing with Miami is the start, not the finish. Sasaki now enters a player-development pipeline designed to move prospects up a strict ladder toward the majors.

Starting in the Low Minors

Sasaki is expected to open his pro career in the Rookie League or at Single-A, the bottom rungs of the minors. The organization’s plan is to give him steady game reps while he adapts to the long bus rides and grueling schedule that define minor league life.

From there the climb runs Single-A to High-A to Double-A to Triple-A. Double-A is the level that matters most: it is where an organization’s top prospects converge, and strong production there can accelerate a player’s timeline dramatically. Given his first base/DH profile, Miami appears to be mapping out a step-by-step plan aimed at a big league arrival within a few years.

What Stands Between Him and a Big League Debut

The biggest hurdles are the same ones scouts flagged on draft day: limited defensive value, below-average speed, and the challenge of adjusting to the stuff MLB pitchers throw. As a likely first baseman or DH, Sasaki will have to keep posting high slugging and OPS numbers to justify a roster spot — his bat has to carry him.

That means adjusting to wood bats for the first time in his career, while learning to handle high-90s mph fastballs and hard, late-breaking pitches — work he will need to put in during his minor league seasons. Whether he can pair contact and power at an elite level will determine how quickly he reaches the majors.