Hisashi Otsuka, possibly part of the Lion in Winter series. I can find nothing to indicate a fake. Appears to have an authentic signature. The framework and matting are quite expensive. The size of actual print to the visible edge/ matting is 29x21. The entire frame is 37.5 x 29 3/4. The rear of the frame is sealed with brown paper and the print has not been removed.
Unknown, possibly a bitter divorce or kind philanthropist brought this art to me. It was purchased at a Goodwill for $20 and the man who saw me pick it up offered me $200 to just hand it to him before I had even purchased it.
Thank you for submitting your item for appraisal. This appears to be what you suggested, a hand signed serigraph by Hisashi OTSUKA (1947) depicting the parent shishi of the play RenjiShi 連獅子. It appears the offer you received was quite ok. Very few ( larger ) prints by this artist sell above the 200 USD range.