Bhutan, China (mainland) (B), India, Japan (B), Laos, Mongolia (B), Myanmar (B), North Korea (B), Russia (Asian) (B), South Korea, Vietnam.
Vagrant to Cambodia, Philippines, Thailand.
Introduced to Italy (B) (NB), USA (B).
Breeds in eastern Asia, from northern Mongolia, north-eastern through Baikal region to Vitim region in east-central Russia, east to Sakhalin I, and south to Japan, Korea and north-eastern China (eastern Shandong). Winters southern from central Japan and central China western through north-western Thailand and northern Burma to north-eastern India (Assam) and Bhutan.
Records from north-western Bangladesh usually ascribed to Common Quail (Coturnix coturnix), but may actually be this species. May breed in Buthan and Burma. Introduced to Hawaiian Is.
 
Population
Estimated population is unknown (2010) and decreasing.
Japanese Quail (Coturnix japonica) [XC487169]
by Stanislas Wroza from Kabansky District, Buryatiya Republits, Russian Federation (flight call, nocturnal flight call)
Japanese Quail (Coturnix japonica) [XC266701]
by Albert Lastukhin from Khasanskiy rayon, Primorskiy kray, Russian Federation (song)
Subspecies
Forms a superspecies with Common Quail (Coturnix coturnix), and possibly also with Stubble Quail (Coturnix pectoralis). Has also been considered a subspecies of Common Quail (Coturnix coturnix), but they are apparently sympatric in Mongolia.