It appears as though Yu Darvish was playing with fractured right index finger.
The Fighters announced the injury today after Darvish was checked out at a Sapporo hospital on Monday.
Sounds like it's a hairline fracture that will keep Darvish out of action for at least 2-3 weeks.
Darvish apparently suffered the fracture sometime on 10/28 during practice when he felt some pain in the finger. He probably didn't think much of it at the time since he never reported it to any of the staff members.
The fracture is in the middle phalanx of the right index finger.