Yoshitomo Tsutsugo was left out of the starting line-up against Orix on June 15 because of tightness in his upper body (right side or back, depending on source). He is not expected to require time off the active roster and is considered day-to-day.
[UPDATE 6/25 @ 12:10pm]
Tsutsugo returned to the starting line-up on June 22 after he started five straight on the bench. He hit a home run on June 24, his first since June 10.
Source: Sponichi 6/25/2018