Cettia diphone, commonly known as the Japanese Bush Warbler, is a small songbird native to Japan, Korea, and parts of China. Its plumage is typically olive-brown with a pale underside. Known for its melodious call, it inhabits forests and gardens, often elusive yet vocal during mating season.

Cettia diphone, commonly known as the Japanese Bush Warbler, is native to East Asia. Its geographical distribution includes Japan, the Korean Peninsula, and parts of eastern China. It is also found on some Russian islands in the Sea of Japan.

The Japanese Bush Warbler typically inhabits temperate and subtropical regions. It is commonly found in dense undergrowth of forests, bamboo thickets, and areas with abundant shrubbery. The climate in these regions is characterized by mild to warm temperatures with seasonal variations, including wet summers and cold winters.

This species occupies a niche as an insectivore, feeding primarily on small insects and spiders found within the foliage. The dense vegetation provides both food and protection, making it an ideal habitat for breeding and raising young. The Japanese Bush Warbler is well adapted to living in both lowland and mountainous regions, often occupying areas from sea level up to 1800 meters. Its song is a distinctive feature, used for communication and territory establishment.