How long can it take to learn japanese(to read and understand, not speaking)?

Question:

It's kinda look impossible to me but I really wanna learn japanese. 'cause I REALLY love J-horror unique style and Momoiro Clover.

Currently I can't read,write and understand Japanese at all except Okasa=Mother that's all I know at this time Lol

Answer:

"Momoiro Clover" are a young Japanese girl group. so I assume you are of the same age. A great age to be learning another language, be it Japanese, Chinese or Korean etc.
I would say that one of the problems in learning the language is in overcoming the "Cultural gap". Japanese is spoken by people from a social and cultural background entirely different from your own, and you will find that the learning process is made much easier if you read some books on Japanese society and culture.
I'm not saying for one minute that the language is easy to learn, far from it. All I'm saying is that you are young and your mind is not all cluttered up with adult things as yet and this is the time to study. Who knows, one day you may be able to communicate with those six girls you so admire.

Take the bull by the horns buddy and go for it, Good luck.