English: Source: Statistics Bureau of Japan "Historical Statistics of Japan"(1914-54) https://warp.da.ndl.go.jp/info:ndljp/pid/11423429/www.stat.go.jp/english/data/chouki/10.html

"FEPC INFOBASE 2020" page 23, (1955-2019) https://www.fepc.or.jp/library/data/infobase/index.html

EIA data was used for hydro without pumped storage for 2016-19, which I felt was important since pumped storage is seldom included in national data. It seems like generation from biomass isn't included in the FEPC data, this would lift the renewable generation pre fokushima above negligible levels if you'd follow the EIA data. But better not mix sources too much I'm thinking.

From Statistics Bureau of Japan I only got thermal generation and the data set ends at 2012, but I assumed all pre- 1955 generation was coal based, since other generation was negligible at 1955. If there is a Statistics Bureau of Japan dataset for the whole period, that also divides thermal (and maybe even splits away pumped storage for the whole time period), this would be optimal. But I doubt it exist.