Assalamu'alaykum. Ohayou minna. Good Morning. Today is the first fasting in 1436 H. aaakkkkk finally Ramadhan is coming.

When entering this holy month, people usually like to congratulate each other on the fasting month like "Happy Fasting" or "Selamat Berpuasa". and how about to say "Happy Fasting" in Japanese? Let's see this explanation from Taka sensei :D.

"Happy Fasting" easily translated into Japanese like "Danjiki Omedetou (" Danjiki "= fast {puasa}," Omedetou "= Happy {Selamat})". However, for most literal Japanese translation of this may seem a little strange, though there are no problems whatsoever in terms of Japanese grammar. Why? Because in Japan the majority population are not Muslims. so they are too strange with the term "Danjiki (fasting)". 

Thus, now there is the best greeting that Taka sensei noticed, that "Happy (welcome) Ramadhan". This speech translation into Japanese is "Yoi Danjikizuki O" ("Yoi ~ o" = congratulations, "Danjikizuki (断 食 月)" = Ramadhan). In his opinion, the translation seemed very "neutral", because different from "Danjiki Omedetou", for Muslims and non-Muslims have absolutely no problem in terms of translation.

So I can conclude that the best "Happy Fasting" greeting in Japanese is used "Yoi Danjikizuki O".

Yoi Danjikizuki O minna :D. Strengthen your Imaan, Heal your Heart. 

Source : 
http://jepang-iwanfals.blogspot.com/2012/08/sekali-lagi-tentang-terjemahan-selamat.html
http://jepang-iwanfals.blogspot.jp/2012/07/danjiki-istilah-puasa-bagi-orang-jepang.html