Japanese radicals presented as learning cards. Start learning here!
The Japanese written system comes from the chinese one. So the japanese radicals or "bushu" comes from the chinese Kangxi radical. With the years it has evolved a bit differently, but they remain very similar.
It gets a bit complicated because not all radicals are recognized by the ministry of education in japan (Or at least I have seen multiple interpretations, and extended radicals).
The Japanese ministry of education released the JΕyΕ kanji which is the official kanji dictionary (writing, meaning, pronunciation). This would be the base for our radicals.
Japanese kanjis have both a chinese "Onyomi" and japanese "kunyomi" pronunciation.
First radical kanji list comes from kanjialive, however radicals were all written in utf-8 chinese instead of japanese, so I combined it with wikipedia kanji list which for some had different meanings.
So I cross checked with jitenon an online japanese dictionary and jlearn for learning japanese and radicals.
And other website I came into while looking into this subject: