Mori was a pitcher for the Lions from 1997 to 2005. He was drafted by the Lions from Nippon Steel Kimitsu of the corporate leagues in the second round of the fall 1996 draft. After a couple seasons working as both a starter and reliever for the Lions he became the closer in 2000 and had 23 saves with a 1.83 ERA. He lost his closers job to Kiyoshi Toyoda in 2001 however and moved into a middle relief role that he excelled at for a couple seasons.
He asked the Lions to post him following the 2005 season and Tampa Bay won his rights for $1,000,000. He tore his labrum during spring training with the Devil Rays in 2006 and ultimately never pitched for them. Tampa Bay released him in the middle of the 2007 season and he spent another year or so attempting to heal and rehabilitate.
He joined the Ishikawa Million Stars of the independent Baseball Challenge League as a player/coach in 2009 and became the team's manager in 2010 after retiring from playing. He lead the team to the BC League championship in 2010 and 2011. He started pitching again for the team in 2013, becoming player/manager while leading the team to another championship. He left the Million Stars after the 2014 season (giving the reigns of the team over to Julio Franco) and became the Lions farm team pitching coach. He was promoted to be the ichi-gun pitching coach in the middle of 2016.
He pitched in four Nippon Series for the Lions (1997, 1998, 2002, 2004) and made five All Star teams (1998, 2000, 2002-04). He won the Pacific League Middle Relief Award in 2002 and 2003.
|1997 BBM #455|
|1998 BBM All Stars #A43|
|1999 BBM Lions 20th Anniversary #SL6|
|2000 BBM Diamond Heroes #26|
|2001 Broccoli #007|
|2002 BBM 2nd Version #685|
|2003 Calbee #129|
|2004 BBM Nippon Series #02|
|2005 BBM 1st Version #2|