Takayuki Kishi has not mentioned anything to the media, but there is a chance he could exercise his option. He does enjoy playing for the Seibu Lions, but is also interested in finding out what kind of value he has on the free agent market.
If Kishi decides to exercise his option, a number of teams will most likely be interested, beginning with the Rakuten Eagles. The Eagles could have a slight advantage over other teams (not including Seibu) since they are located close to his home town in Sendai.
The Lions may have already approached Kishi with a multi-year extension.
[UPDATE @ 11:42pm]
Kishi has an international FA option and may have some interest in playing in the Majors.
Source: Sanspo 9/27/2016
[UPDATE 9/28 @ 2:09pm]
The Rakuten Eagles are very interested in Kishi and could offer him a sizable multi-year deal, if he decides to test the free agent market. Their offer could be bigger than his current deal with the Seibu Lions (three years, 1.2 billion yen).
Source: Nikkan Sports 9/28/2016
[UPDATE 9/29 @ 1:30pm]
The Lions may have offered Kishi a two-year deal worth around 500 million yen. They could keep their offer on the table even if he decides to exercise his option (something they usually do not do).
Source: Sports Hochi 9/29/2016
[UPDATE 10/12 @ 6:57am]
It might be down to two options for Kishi: return to Miyagi (Rakuten) or stay in Tokorozawa (Seibu). There are several problems with either option. Kishi has struggled with injuries the last few years and may be concerned about the cold weather in Miyagi. The Lions spent a lot on Ernesto Mejia and might not have quite as much left to spend on Kishi.
Heading overseas is also an option, but there might not be a lot of interest because of his injuries.
Source: ZakZak 10/11/2016
[UPDATE 10/30 @ 7:03pm]
Kishi is strongly considering exercising his free agent option. He may have already told the Lions about his desire to test the market. He is probably not interested in the international market.
[UPDATE 11/1 @ 5:06pm]
The Lions still have one last final meeting with Kishi. They plan to wait for a good reply, even if he decides to exercise his free agent option. They are not planning to make changes to their offer since they believe it is solid.
Source: Sponichi 11/1/2016
[UPDATE 11/2 @ 4:00pm]
Kishi told the media after practices at Seibu Prince Dome today that he wanted to test the free agent market. He is not necessarily looking to leave the team, but might if he gets a better offer.
Rakuten Eagles Vice Chairperson Senichi Hoshino seems ready to jump into negotiations as soon as Kishi officially becomes a free agent.
[UPDATE 11/3 @ 12:19pm]
The Seibu Lions are not planning to get into a bidding war to keep Kishi. They feel they offered him a fair deal.
Source: Daily Sports 11/3/2016
The Rakuten Eagles might be preparing the uniform number 11 and a four-year deal that could be worth as much as 1.6 billion yen (total would include incentives and bonuses). The Seibu Lions’ offer is believed to about about 1.0 billion yen over four years.
Source: Sports Hochi 11/3/2016
[UPDATE 11/3 @ 10:00pm]
The Lions may have offered Kishi up to four years at about one billion yen (total).
Source: Nikkan Sports 11/3/2016
[UPDATE 11/3 @ 10:30pm]
The Eagles might offer Kishi a three-year deal worth over 1.2 billion yen and the uniform number 11.
The Lions may have first offered a two-year deal. Their last offer may have been four years.