Go Noto CJKCore2005
CJKCore2005 provides a basic CJK subset of ~10000 characters in mainstream use in East Asia, including Chinese (Traditional, Simplified), Japanese (Hiragana) and Korean (Hangul) variations. It covers the Unihan IICore subset as specified by the Unicode IRG team in 2005.
This font was created from the NotoSansCJKsc-Regular.otf which defaults to Simplified Chinese, but the OpenType features can be used in your editor/word-processor/etc. to switch to Japanese/Korean etc.
This font is about 1/3rd the size of the original.
Other fonts (South Asia, etc.) have not been changed, so you can download them from v2.0 Release below.