謎 | A mystery! A puzzle. Like you’d see this in the title of detective novels. The Mystery Of The Mummy’s Curse!!! |
不思議 | Weird. Very broad – not limited to scary or supernatural situations. Can be used about a person, or a situation, or even a flavor. Something about this soup tastes weird! $$$ |
ふかかい | A written, as opposed to spoken, word: incomprehensible, something you can’t figure out. WWW |