Google actually has an official dictionary popup Chrome app.
It's called Google Dictionary.

Link:
https://chrome.google.com/webstore/detai...ja/details

So far there's no support for Japanese.
But there is support for Chinese and Korean.

It current supports:
- Chinese (Simplified)
- Chinese (Traditional)
- Czech
- Dutch
- English
- French
- German
- Italian
- Korean
- Portuguese
- Russian
- Spanish

I assume at some point in the future they'll add Japanese support.

do it for android and i'll burn my IOS devices :p