http://www.major.jp/japanese/mori/profile_mori.html
That's one place you can find his year-by-year stats.
In the "DATA" section, the columns, from left to right, are
Year, Team (all years, he played with Seibu Lions), Number of games, Innings Pitched, Win, Loss, Saves, Runs, Earned Runs, Hits, Homeruns, BB, and ERA.