Sponichi has posted a couple of articles (see below for links) that point to the possibility of Yokohama Ni-gun manager Kazuyuki Shirai being a candidate to replace Masataka Nashida as manager of the Nippon Ham Fighters next season.
Shirai was selected in the first round of the 1983 draft by the Nippon Ham Fighters and after retiring, joined the organization as a coach -- Ni-gun general coach in 2000, Ni-gun manager in 2001, and Ichi-gun head coach in 2003 (the high point was winning the Nippon Series with Trey Hillman in 2006). He also spent a year as a special coach / scouting advisor with the Kansas City Royals in 2008. The Bay Stars then hired Shirai to be their Ni-gun manager in 2011.
Since Shirai knows the Fighters organization fairly well, it seems like he would be the perfect fit to replace Nashida. The only problem is, the Bay Stars also think highly of him and could be considering him the next in line to replace their Ichi-gun manager, Takao Obana.