The most comprehensive Japanese dictionary?

Hell everyone. I'mm starting to learn Japanese. But I couldn't find out what is the most comprehensive Japanese dictionary for english or vietnamese.

Can anyone suggest me ?

Have you tried translation apps you can download for free?
They work off-line (no need for Internet connection).

Yes, I have tried few, but they're add-ons to browser not the complete dictionary that i expected.

I normally use http://jisho.org/ or an app called imiwa? Both are for free and have a lot of entries. If you are just starting to study I think they should be sufficient and they are free. Imiwa? Is also available offline.

WWWJDIC is a staple from Japanese-to-English, though it is community-sourced to a degree. Linguee.jp and ejje.weblio.jp/sentence/, though not technically dictionaries, can both provide valuable example sentences if you paste in difficult-to-understand Japanese words.

Kenkyuusha's is the best there is. Period. Lots of editions available including romanised, iOS apps, etc. Most free bilingual dictionaries including those mentioned above use the same database. They are riddled with poor or incorrect example sentences, and while the definitions can be useful for J-E, as E-J dictionaries they fall well short.

Please note, though, that a Kenkyuusha's going to set you back about US$100. It's a good tool, but keep in mind that it has the same problem with listing archaic/awkward translations that other major online dictionaries do. (This is, unfortunately, a chronic problem with JA-EN/EN-JA dictionaries.)

If you're just starting out, then a basic paperback dictionary or an online dictionary will be just fine for the words you'll be learning. Once you get into more advanced vocabulary, things might become a little stickier - though the good, major online dictionaries aren't quite the minefield that Liz suggests.