is a Japanese professional baseball shortstop with the Yomiuri Giants of Nippon Professional Baseball (NPB).
In , Sakamoto became the first player in Giants franchise history to start a season opener while under the age of 20 since Hideki Matsui.
Early life and high school career
Sakamoto was born in Itami, Hyōgo, and began playing baseball while in the first grade at Koyanosato Elementary School for the Koyanosato Tigers (a Little League team) alongside former New York Yankees pitcher Masahiro Tanaka. Ironically, Sakamoto was the team's ace pitcher, and Tanaka his batterymate on the team. Both Sakamoto and Tanaka went on to attend Itami Municipal Matsuzaki Junior High School, but Sakamoto opted to join Itami Senior, while Tanaka chose to play for the Takarazuka Boys.
Upon graduating from junior high, Sakamoto attended Kosei Gakuin High School in northern Aomori Prefecture, a baseball powerhouse in the Tōhoku region. He became the team's starting shortstop by the fall of his first year (the equivalent of tenth grade in the United States) at Kosei Gakuin High. Sakamoto was hitting cleanup by the summer of his second year (eleventh grade), and led his team to runners-up in the Tohoku Regional Tournament that fall, earning a berth in the 78th National High School Baseball Invitational Tournament that would be held at Koshien Stadium the following spring. He attracted the attention of scouts when he hit .813 (13-for-16) with four home runs in the Tohoku Regional Tournament later that spring, and hit a total of 39 home runs during his high school career.
The Yomiuri Giants picked Sakamoto in the compensatory first round of the NPB high school player draft after losing to the Chunichi Dragons in the lottery that was held for fellow shortstop Naomichi Donoue, the most coveted high school position player, and presented Sakamoto the uniform number 61.
Professional career
In 2007, Sakamoto spent most of his rookie season () with the Giants' nigun team (Japanese for "minor league" or "farm team"). He played 77 games in the Western League, hitting .268 with five homers and 28 RBIs. Sakamoto saw his first call-up to the ichigun (major league) team in July and made his professional debut as a pinch runner on July 12. He recorded his first career base hit and RBI on September 6, knocking in the game-winning run in a game against the Dragons.
In 2008, Manager Tatsunori Hara had high hopes for Sakamoto in the season, playing him in all 15 pre-season (spring training) games at either shortstop or second base. Although Tomohiro Nioka, then the Giants' starting shortstop, returned from injury just before their season opener, Sakamoto's quick adjustment to second base, accompanied by left-hander Masanori Ishikawa's taking the mound for the opposing Tokyo Yakult Swallows, prompted Hara to start him in the season opener as the No. 8 hitter on March 28. Sakamoto became the first Giant to start a season opener while under the age of 20 since former New York Yankees outfielder Hideki Matsui did so in 1994.
Although Sakamoto was expected to platoon at second base with the likes of veteran journeyman Kimura Takuya and speedster Ryota Wakiya throughout the season, he returned to his natural position when Nioka tore his right calf muscle in that very game. Sakamoto started at shortstop from the second game onwards and never gave up the starting job. His first career home run came against the Hanshin Tigers on April 6, a grand slam off reliever Kenta Abe that made him the youngest player in Central League history (19 years, 114 days) to hit a grand slam in a regular season game. He was also voted to the All-Star team that year, getting his first hit in an All-Star game in Game 2 held at Yokohama Stadium on August 1.
Sakamoto finished the season with a .257 batting average, eight home runs, 43 RBI and 10 stolen bases, contributing to the Giants' league title that year. He made his first appearance in the Japan Series against the Saitama Seibu Lions on November 1, hitting a home run off veteran right-hander Fumiya Nishiguchi in Game 7 and becoming the first NPB player in 22 years to hit a home run in the Japan Series while being under the age of 20 (Kiyohara Kazuhiro last accomplished the feat while he was with the then-Seibu Lions). The Giants lost Game 7 3-2, coming up short in their run for a Japan Series championship.