Norichika Aoki

In 2004, Aoki saw little playing time in his rookie season (2004), playing just 10 games at the ichigun (Japanese equivalent of "major league") level. However, he showed signs of promise in the minors, hitting .372 and leading the Eastern League in both batting average and on-base percentage (.436) and coming second in stolen bases (21). In the Fresh All-Star Game (the Japanese equivalent of the All-Star Futures Game) held that year, Aoki went 4-for-5, coming a home run short of the cycle and winning Most Valuable Player honors for the game.

In 2005, Aoki enjoyed a breakout year in 2005, earning the job of starting center fielder with the departure of Atsunori Inaba. While he struggled in the opening weeks of the season as the Swallows' No. 2 hitter, striking out uncharacteristically often, he slowly began to collect hits at his usual pace and was promoted to the leadoff role by June 2005. On October 6, 2005, he tied the Central League single-season hit record of 192 (set by Robert Rose in 1999), following up the feat by becoming the second player in NPB history (after Ichiro Suzuki) to record 200 hits in a single season, on October 11, 2005.

In 2006, Aoki was chosen to play in the inaugural World Baseball Classic as a member of the Japanese national team in 2006. He made his second All-Star appearance in July 2006 and was named the Most Valuable Player in Game 1 (held at his home park, Meiji Jingu Stadium), becoming the fourth player in NPB history to win both Fresh All-Star Game and All-Star Game MVP honors.

On December 25, 2006, Aoki publicly stated his intent to eventually play in the major leagues via the posting system, saying, "…I would like to move to the majors after some years. It might be difficult to do so as a free agent since I'll be over 30 by then." While major league teams expressed interest in Aoki (especially after seeing him in international play), the Swallows offered no indication of their willingness to comply with the request.

Aoki was named to the Japanese national team for the first time in early 2006 for the inaugural World Baseball Classic. After being relegated to the bench and seeing little playing time in the first two rounds, he was named the starting center fielder in the semi-finals against South Korea and finals against Cuba, but went 0-for-4 in those two games and finished with just one hit in five at-bats in the tournament. Nevertheless, Japan defeated Cuba 10-6 in the finals to become the inaugural tournament champions.

On the defensive end, Aoki has earned a reputation as a superb center fielder with excellent instincts and range, winning three consecutive Golden Glove awards from 2006 to 2008 and leading all outfielders in the Central League putouts in 2006 and 2007. His throwing arm is fringe-average for a major league center fielder but accurate, and he has a quick release. In his first MLB season, Aoki made nine putouts in a game while fielding the right field in the Brewers' win over the Reds on June 8, 2012, falling one catch shy of the National League record. The 9 putouts rank among the most by a Brewers outfielder in a game. He was known throughout the Brewers organization as a solid defender.

In 2007, Aoki and teammate and fellow outfielder Alex Ramírez competed for the batting title at a torrid pace throughout the 2007 season. On July 10, 2007, Aoki became the fastest player in Japanese professional baseball history to amass 500 career hits, doing so in 373 games. While he fell short of 200 base hits, partly due to the 80 walks (fourth in the league) that opposing pitchers issued to him, he finished second in the league in hits (to Ramírez, who hit safely 204 times, a new Central League record) with 193, winning his second batting title with a .346 average. Aoki also led the league in on-base percentage for the first time and scored 114 runs (his third consecutive season with 100 or more runs).

Meanwhile, his stolen base total dropped sharply from 41 to 17, a decline that could be attributed to then-player-manager Atsuya Furuta's placing Hiroyasu Tanaka (rather than Adam Riggs, as was the case in 2006), a second baseman with little power, behind Aoki in the 2-hole and instructing him to bunt often. On the other hand, Aoki began to show legitimate power, hitting 20 home runs and slugged over .500 for the first time. He was slotted into both the 2- and 3-hole numerous times and even hit cleanup in Furuta's retirement game as a player on October 7, 2007.

Aoki played in the Asian Baseball Championship as a member of the Japanese national team in December 2007, helping Japan clinch a berth in the upcoming Beijing Olympics.

Aoki played in the 2007 Asian Baseball Championship (which also functioned as the Asian qualifying tournament for the Beijing Olympics) as a member of the Japanese national team. Though he was 0-for-9 with one sacrifice bunt in the first two games against the Philippines and South Korea as Japan's No. 3 hitter, he went 3-for-4 with a double and a walk in a 10-2 mercy rule win in the final game against Taiwan, helping Japan clinch a berth in the upcoming Olympics.

On May 5, 2008, Aoki was scratched from the lineup and sent down to the minors due to an oblique strain. It was his first time missing playing time due to injury since his debut at the ichigun level. However, he returned some three weeks later on May 29, 2008, engaging in another race for the batting title, this time with Yokohama BayStars left fielder Seiichi Uchikawa.

In August 2008, Aoki was chosen to play in the 2008 Beijing Olympics along with teammate Shinya Miyamoto as a member of the Japanese national team. After he returned to the Swallows, manager Shigeru Takada opted to use him in the 3-hole permanently, slotting newly acquired left fielder Kazuki Fukuchi into the leadoff role instead. While Aoki relinquished the league lead in both batting average and on-base percentage to Uchikawa, he finished the season with a personal-best batting average of .347, striking out just 47 times (fewest in the league among qualifying players) and swiping 31 bases (second to Fukuchi on the Swallows).

Aoki played in all nine games in the 2008 Beijing Olympics as Japan's starting center fielder, batting in each of the first three spots in the order and hitting .294 (10-for-34) with seven RBI and scoring five runs. Japan dropped the semi-finals against South Korea, though, and despite a go-ahead three-run home run by Aoki in the third inning of the bronze medal match against the United States, Japan went on to lose 8-4 in a disappointing fourth-place finish behind South Korea, Cuba and the United States.

In 2009, Though he hit well in the second World Baseball Classic, Aoki struggled in the opening weeks of the 2009 season, hitting just .233 with a .316 on-base percentage in April 2009. He got hit in the head by a pitch thrown by Chunichi Dragons closer Hitoki Iwase on April 30, 2009, but was found to have no serious injuries upon diagnosis.

Aoki played in the World Baseball Classic for the second time in 2009, having no difficulty playing left field despite manning center field almost exclusively for the Swallows. He played in all nine games, hitting .324 (12-for-37) with seven RBI as Japan's No. 3 hitter, and had a pivotal role in Japan's repeat as tournament champions. Aoki was one of three outfielders named to the All-Tournament team.

The Swallows posted Aoki to Major League Baseball in the 2011–12 offseason. The Milwaukee Brewers won the posting and signed Aoki in January 2012 to a two-year contract with a third-year option. He became the team's first Japanese player to be acquired through this process. Kosuke Inaji served as Aoki's interpreter throughout the season.

On June 7, 2012, in a game against the Chicago Cubs, Aoki hit his first out of the park home run in his MLB career. He then hit a second home run in the bottom of the tenth inning, breaking a 3–3 tie. It was his first career walk-off, and his first career multi-home run game. During the later portion of the season, Aoki has started to become a spark plug for the Brewers. He made great defensive plays and got big hits when they were needed, including a 2 out, 2 strike, 2 run home run on September 9, 2012, against St. Louis to tie the game and send it to extra innings. This game was needed by the Brewers to help push them toward a possible Wild Card berth.

On June 24, 2012, Aoki collected 3 hits and 4 stolen bases against the Chicago White Sox. The 4 stolen bases tied the Brewers franchise record.

In 151 games in 2012, he hit .288 with 10 HR, 50 RBI, 37 doubles, 30 SB (9th in the NL), and 43 walks, giving him a .355 OBP. He finished 5th in the NL Rookie of the Year voting.

Aoki was the Brewers Opening Day right fielder and leadoff hitter in 2013, and Logan Schafer was his main backup. In May 2013, he hit .343 with 6 RBI, bringing his season average to .299. After that, he had a steady decline until September 2013, when he hit .297 with 6 RBI and 15 walks. In 155 games, he hit .286 with 8 HR, 37 RBI, 20 SB and 55 walks, giving him a .356 OBP.

On December 5, 2013, the Brewers traded Aoki to the Kansas City Royals for Will Smith. Aoki batted leadoff for the Royals for much of the 2014 Kansas City Royals season. For the season, he batted .285/.349/.360, in 491 at bats.

On August 6, 2014, in a game against the Arizona Diamondbacks, Aoki hit a grand slam in the fifth inning off of relief pitcher Bo Schultz. This was his first career grand slam, as well as his first (and only) homer with the Royals. Aoki also set a Royals franchise record, which was the most hits in a three-game series. He collected a total of 11 hits against the Chicago White Sox at Kauffman Stadium, passing Willie Wilson and George Brett's former record of 10 hits.

On January 19, 2015, Aoki signed a one-year deal with the San Francisco Giants. On May 3, 2015, in a 5-0 win over the Los Angeles Angels of Anaheim, Aoki led off the first inning with a solo home run against pitcher Jered Weaver. Following Aoki was teammate Joe Panik batting second, who homered as well. It was the first time since 1964 that the Giants had opened a game with consecutive home runs.

On June 20, 2015, Aoki was hit by a pitch from Dodger Carlos Frias, breaking his right fibula and putting him on the disabled list, resulting in him missing 28 games. At the time he was batting .317 and was a potential All-Star, leading the league in several offensive categories. Two weeks after his return on July 27, 2015, he was again hit by a pitch, this time in the batting helmet by Chicago Cubs pitcher Jake Arrieta. He went on the 7-day concussion list, missing another seven games.

In 2015, he batted .287/.353/.380 in 355 at bats. After the 2015 season, the Giants declined Aoki's option, making him a free agent.

On December 3, 2015, Aoki signed a one-year, $5.5 million contract with the Seattle Mariners.

The Houston Astros claimed Aoki off waivers from the Mariners on November 3, 2016.

On June 11, 2017, Aoki recorded his 2000th career professional hit against the Los Angeles Angels of Anaheim. This includes hits in NPB and MLB. While he was traded before the Astros' World Series championship run in 2017, he was awarded a World Series ring by the team by virtue of playing 70 games for them in 2017.

On July 31, 2017, the Astros traded Aoki and Teoscar Hernández to the Toronto Blue Jays for Francisco Liriano. He was designated for assignment on August 28, 2017, and released the following day.

On September 2, 2017, the New York Mets signed Aoki to a major league contract. On October 30, 2017, Aoki was released.

Aoki played center field for Team Japan in the 2017 World Baseball Classic. His team finished 3rd.

On January 30, 2018, Aoki signed a three-year deal to return to the Tokyo Yakult Swallows, where he spent the first eight years of his professional career. In early May, 2018, Aoki recorded his 4,000th at bat in NPB. With a .328 career batting average to that point, he then qualified as NPB's lifetime batting champion. He was selected for the 2018 NPB All-Star game [jp].