JAPANESE BUSH WARBLER (Horornis Diphone) – (See images below)
DESCRIPTION: The Japanese Bush Warbler has brown top parts and grey under parts. The bill is grey and the legs are pinkish-grey. It is around 6 inches (15 cm) long.
VOICE: https://www.xeno-canto.org/species/Horornis-diphone – see also video below.
NAME: The English name ‘warbler’ means to sing with trills. The Latin genus name ‘Horornis’ stems from ‘mountain’ and ‘bird’, and the species name ‘diphone’ means ‘many tongues’. The Japanese bush warbler has several other names in Japan: ‘spring announcing bird’, ‘spring flower viewing bird’, ‘poem reading bird’, and ‘Japanese nightingale’.
HABITAT: In its native range: forest at higher elevations during the summer, and at lower elevations during the winter.
DIET: Japanese bush warblers are omnivorous and their diet follows what’s available during the seasons – insects and arthropods in the summer, seeds in the winter.
NESTING: The nest is a bowl-shaped structure with a side entrance. An average of five eggs are laid, and females care for the chicks.
DISTRIBUTION: The native range of this warbler is mainly Japan and surrounding regions. It is partly migratory. It has been introduced to Hawaii around 100 years ago, and since then has settled in the forests, both native and non-native, in all of the main Hawaiian islands.
CONSERVATION: Although the Japanese bush warbler is a popular cage bird in Japan thanks to its singing ‘skills’ and cultural importance, it is still evaluated as ‘least concern’.
NOTES: The Japanese bush warbler is a secretive bird, which remains hidden in bushes during the day. However it is easy to hear across much of Japan in the spring. This bird is also frequently referred to in Japanese poetry, and is considered as a herald of spring. The droppings of this species have been an ingredient to make a skin-whitening cream. It has been used by geishas and actors for centuries.
REFERENCES: https://en.wikipedia.org/wiki/Japanese_bush_warbler

Japanese Bush Warbler - Aichi, Japan - Mar. 2014 - photo by Alpsdake
Japanese Bush Warbler – Aichi, Japan – Mar. 2014 – photo by Alpsdake

The video below was taken in 2013 on the island of Sakurajima, Japan. In spite of doing my best to locate that singing individual I was unable to locate it. It also kept changing locations around me.