For me, it looks like a Blue and White Flycatcher of the subspecies
intermedia (the subspecies that breeds in mainland Asia rather than Japan). This has a blue wash on the breast which can suggest similarity to Zappey's (
cumatilis). I would expect Zappey's to be paler and more turquoise-blue with fine black streaking, and with less extensive blackish in the face.
The paper splitting Zappey's contains more details about these taxa:
http://orientalbirdclub.org/wp-c ... peys-Flycatcher.pdf
