Hiromi Oka (right hamstring) has been rehabbing at the Kamagaya facilities. He could be ready to play in his first Ni-gun rehab game in early-September. If things go well from their, he might be able to join the active roster before the end of September.
Oka has already resumed playing catch and taking batting practice against pitching machines.
Source: Sports Hochi 8/25/2016