Learning Japanese is a long and arduous task but there are ways of learning the language an easier way. Especially when living in Japan.
Teach kids. If you can choose between teaching children and adults, choose children. They are doing the same thing you are – learning the basics of a foreign language. I’ve learned tons of words from repeatedly teaching words in English and hearing the Japanese equivalent from them.
Listen to Japanese music. Just listening will help.
Watch Japanese TV variety shows. These shows have the annoying yet highly useful habit of displaying large cartoony Japanese of what they are saying as they are saying them. It’s a really good way to learn kanji.
Watch the learn English TV shows and repeat the explanations of the barbarian’s English into beautiful Japanese.
Get a non-English speaking Japanese girlfriend/boyfriend and speak only Japanese with him/her. You’re young. You’re in love. Language doesn’t matter.
Get Japanese friends. Take up a hobby and join a group – Taiko drumming, indoor football or karate.

I’m doing my best to not learn any more Japanese than I need to. I find my ability to speak English degrades as my Japanese gets better. And of course, speaking English is my livelihood!
good luck with your English livelihood!
I think my Japanese goes well just like my English, that’s because speaking both is my livelihood! aikawarasu gambarimasu yo!
I’m doing my best to learn more Japanese, but I have the exact problem as ‘Contamination’, though it’s not a problem for me to loose English, because I’m planning on being a ‘permanent’ resident,in Japan, an my occupation, it doesn’t matter if i can or can not speak English. ^^
hello