The spotted double wing-bars are unique to this conifer specialist. About 21 subspecies usually recognized. Birds in Japan are assigned to P. a. insularis. It is similar to the widespread nominate race in having white nape and cheek patches, blue-gray mantle and white underparts. It differs in having paler, but more extensive grayish flanks extending to its belly as seen here. It also has small buff spots at the tips of its median coverts which are difficult to see (barely visible in this photo). Canon PowerShot SX60.
References:
Brazil, M.A. (1991) The Birds of Japan. Smithsonian Inst. Press.
Gosler, A. & Clement, P. (2019). Coal Tit (Periparus ater). In: del Hoyo, J., Elliott, A., Sargatal, J., Christie, D.A. & de Juana, E. (eds.). Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona. (retrieved from https://www.hbw.com/node/59874 on 11 April 2019).
Harrap, S. & Quinn, D. (1995) Chickadees, Tits, Nuthatches and Treecreepers. Princeton Univ. Press.