Graceful songbird of well-shaded forests, particularly stream gullies; often in more open habitat in migration. Stunning breeding male purplish-black above and white below, with a short crest, neon-blue eyerings, and long black tail streamers. Female and non-breeding male have dark gray head and chest, paler eyering, shorter crest, and chestnut-brown wings and tail, without streamers. Compare with female and non-breeding male Amur and Blyth’s paradise-flycatchers, with which Japanese overlaps on its Southeast Asian wintering grounds. Note Japanese’s contiguous dark gray throat and chest (Amur has a more sharply-demarcated black throat and gray chest), dull darkish wings (Blyth’s has brighter rufous wings), and fairly clean demarcation between gray breast and white belly (Blyth’s has a more gradual fade). Song a run-on series of coarse whistles; call a rough, nasal “bee.”