Cuculus hyperythrus

The northern or rufous hawk-cuckoo (Hierococcyx hyperythrus) is a cuckoo found in eastern China, North and South Korea, far-eastern Russia and Japan; northern populations migrate to overwinter in Borneo. This elusive species is considered rare over most of its range and many of its life-history traits remain understudied. It perches in the crowns of tall trees, making direct observation difficult. (Wikipedia, general species account)

It was once considered the same species as the Malaysian and Hodgson's hawk-cuckoos, all three since split. Hawk-cuckoos are so named because their broad, rounded wings and plumage give them a great resemblance to Japanese and Chinese sparrowhawks. (Wikipedia, general species account)