Chunichi Dragons Ichi-gun Strategy and Fielding Coach Hatsuhiko Tsuji is the front runner for the Seibu job.

Other possible changes:

Infield/Base Coach Hiroshi Narahara not returning in 2017

Ni-gun Hitting/Outfield/Base Coach Katsuhiko Miyaji not returning in 2017

Head/Pitching Coach Tetsuya Shiozaki reassigned to Ni-gun, possibly Ni-gun manager

Strategy Coach Hideki Hashigami could be named head coach

Pitching Coaches Yoshihiro Doi and Shinji Mori are expected to return in 2017

Hitting Coach Shigenobu Shima is expected to return in 2017

Norio Tanabe could remain in the organization and get a job in the front office

Source: Daily Sports 9/29/2016, Sponichi 9/29/2016, Sports Hochi 9/29/2016, Nikkan Sports 9/29/2016, Tokyo Sports 9/29/2016, Seibu announcement (Narahara, Miyaji)

See also:

[UPDATE 9/30 @ 7:21am]

The Lions formally offered Tsuji the job on September 29.

Source: Sanspo 9/30/2016, Sponichi 9/30/2016

[UPDATE 10/3 @ 5:51am]

The Lions announced on October 2 that they were going to hold a press conference on October 3. No specifics were listed, but the media is expecting an announcement about Tsuji taking over as the new manager.

Source: Daily Sports 10/2/2016, Nikkan Sports 10/2/2016, Nikkan Sports 10/2/2016, Sports Hochi 10/2/2016