- Bats Left, Throws Left
- Height 6' 2", Weight 185 lb.
- High School Funabashi High School
Masanori Hayashi has pitched for several years in Nippon Pro Baseball.
Due to a foot fracture in high school, teams that were interested stepped back. He was picked in the 7th round in 2001 by the Yomiuri Giants. He debuted in Nippon Pro Baseball in 2003, going 3-3 with a 3.22 ERA and 87 strikeouts in 72 2/3 IP.
Hayashi had a 3-9, 4.89 record in 2004. He moved to the bullpen in 2005 and did very well, going 2-2 with 18 saves and a .191 opponent average, fanning 67 in 67 innings. The left-hander was 4-4 with a 2.88 ERA in 2006 with 56 1/3 IP in 62 games as a LOOGY; Katsuhiro Nagakawa took over as closer. He was 4th in the CL in appearances. He was plagued by elbow problems that year but controlled the situation with pain killers. A bone spur was discovered but Hayashi opted against surgery.
Hayashi's shoulder was injured in 2007 and he was 2-1 with 3 saves and a 3.29 ERA in 41 games (38 1/3 IP). In the first All-Star game of that season, he teamed with Koji Uehara, Shingo Takatsu, Atsushi Kizuka, Hitoki Iwase, Tomoyuki Kubota, Hiroki Kuroda, Marc Kroon and Kyuji Fujikawa on a one-hit shutout of the Pacific League All-Stars. He decided to have the bone spur surgery following that campaign. He struggled with control issues in 2008, walking 14 in 10 2/3 IP; he had a 6.75 ERA and no decisions and spent much of the year in ni-gun.
Hayashi was traded with Tomohiro Nioka to the Nippon Ham Fighters for Micheal Nakamura and Takahito Kudoh. He went 3-2 with a 3.32 ERA in 46 games for Nippon Ham in 2009, holding left-handed batters to a .167 average (righties hit .261). He pitched in five of six games in the 2009 Japan Series, which Nippon Ham lost to Yomiuri. In game five, he allowed a game-tying single in the 8th to platoon specialist Noriyoshi Omichi.