>>436159I can't say how Japanese do it, I only know what I do. Let's say I see a word like 脳癌, which contains a character I don't recognize, 癌.
>I know 脳, nou, meaning brain.>look up 脳 on wiktionary for words which contain 癌.>find itThis doesn't work for more obscure stuff, but you're not likely to find obscure stuff.
But if you didn't know 脳, you could also look it up by the meat radical 肉 plus seven strokes:
https://en.wiktionary.org/wiki/Index:Chinese_radical/肉 