The Nippon Ham Fighters announced on October 11 that Shohei Otani will have surgery on his right ankle to treat posterior ankle impingement syndrome at a hospital in Tokyo on October 12.
[UPDATE 10/12 @ 3:10pm]
Otani will most likely need two to three months for a full recovery.
Source: Nikkan Sports 10/12/2017
[UPDATE 10/13 @ 12:03am]
Otani had his surgery on October 12. There were no complications. He will begin a rehab training program during a two- to three-week hospital stay. He is then expected to continue his training at the Kamagaya facilities.
Source: Nikkan Sports 10/12/2017
[UPDATE 10/19 @ 3:10pm]
Assuming no delays with Otani’s hospital post-op recovery, he could be discharged some time around October 26. His recovery has been going smoothly so far. He is slowly regaining mobility in his ankle. He might be able to get around without crutches by the time he leaves the hospitals.
[UPDATE 10/25 @ 3:53pm]
The Fighters announced today that Otani was released from the hospital. He will be a rehab program at the Kamagaya facilities. Otani will need two to three months for a full recovery.
Otani arrived at the Kamagaya facilities in a taxi at around 1:00pm and was able to get around without any assistance (no crutches).
[UPDATE 10/29 @ 1:04am]
Otani will have his first periodic examination on November 9. Assuming no issues, he will be allowed to do some jogging. After that, soft-toss hitting and playing catch. If there are no setbacks, he could resume hitting and pitching practices some time in December.
Source: Sanspo 10/28/2017
[UPDATE 10/31 @ 2:50pm]
Otani did some walking outdoors for the first time since his surgery. He walked back and forth between the foul poles three times.
[UPDATE 11/5 @ 12:16pm]
Otani added stairs to his rehab training on November 4.
Source: Daily Sports 11/5/2017
[UPDATE 11/10 @ 3:06am]
Otani was checked out at a hospital on Thursday morning. He got the green light to add more exercises to his workouts. In the afternoon, he jogged for about ten to fifteen minutes. He also threw some baseballs into a net: thirty while on one knee and sixteen while standing and without a step.
[UPDATE 11/13 @ 12:51am]
Otani started hitting off a tee in front of a mirror during practices on November 12. He swung the bat sixty times in about twenty-five minutes. He will continue to train at the Kamagaya facilities until January next year.
About 200 fans showed up at amagaya for a chance to see Otani a day after he held a press conference to announce that he wanted to go to the Majors.
Corrected batting practice type on 11/13 @ 1:49pm. Added additional information on 11/13 @ 4:27pm.
[UPDATE 11/21 @ 12:52am]
Otani started playing catch on November 20. He threw the ball at a distance of about fifteen meters.
Source: Sponichi 11/20/2017
[UPDATE 11/24 @ 4:19pm]
Otani worked out at an indoor training facility in Sapporo on November 23. After spending time on warm-ups, he threw into a net and played catch with a trainer at a distance of about thirty meters. It was the second time he played catch since he had surgery on his right ankle.
Source: Sanspo 11/24/2017
[UPDATE 11/26 @ 3:16am]
Otani tried running a fifty-meter dash (light running) during workouts on November 25. It was the first time he ran a fifty-meter since his surgery.
Source: Sanspo 11/25/2017
[UPDATE 11/26 @ 7:00pm]
Otani has already started throwing around an MLB baseball.
Source: Sanspo 11/26/2017
[UPDATE 12/13 @ 12:19am]
Otani returned to Japan on December 12 and immediately resumed his rehab training. His workouts include running, playing catch at forty to fifty meters, and, for the first time since his surgery, taking indoor batting practice against a pitching machine.
Source: Nikkan Sports 12/12/2017