rapport

Is there a good translation for "rapport" for using when you want to say you met someone for the first time and just seemed to hit it off well/you just "clicked" with that person?

To say you "hit it off well," there is an expression that goes "hachou ga au/aimasu" (our wavelength meet/fit). Is that what you are asking?

You could say something like:
- Ano hito to wa, hachou ga au mitai desu. (With that person, our wavelengths seem to click/fit.)

- Hachou ga atta you de, ureshii desu. (I am happy that our wavelengths seem to have clicked/met.)

There are many ways to express depending on the context.
"hachou ga au", "ikitougou", "uma ga au", "tuukaa no naka" and many more.
http://thesaurus.weblio.jp/content/%E3%82%A6%E3%83%9E%E3%81%8C%E5%90%8...