Yes, this is a very powerful method to make you fluent in Japanese in only 30minutes. I tried it yesterday and it worked, powerfully!
Simply, just enter a shop that has salesmen who only speak Japanese, and ask them about what you need. Yup, as simple as it sounds, this is a really powerful method to make you -make you, despite your own will- speak Japanese.
Yesterday I went to the post office to make a credit card. After being 10min inside, I found myself surrounded by 2 saleswomen and 5 customers, all looking at me with a weird look, one of them had a smile on her face. I tried to explain to them what I want, Japanese, English, Arabic, Hindi, everything. Nope, Couldnt do it. Saying "credit card" or "Kuredetto Caado" many times will NOT do the job, in opposite to what I have expected.
I entered the post office in a hope of getting a credit card. Since I have a post office account already, I thought this would be easy. I entered and took a number. When my turn came, I headed to the counter and said I wanted a credit card, in Japanese. The employee girl offered me 5 choices, so I asked for the one that can help me buy online. Here, she started saying long sentences in Japanese. No problem so far.
She handed me the application form, and here the problem started. Since I am still a beginner in Kanji reading (the complex Japanese characters) I didnt know what to write. I told her that, so she offered to help me by saying the fields in Japanese. We reached a field, where I had to write something I did not know what it is. Not my name, not my address, not my data. She tried to explain, I couldnt understand. She tried again, I couldnt. Then, she called her employee friend, who tried to explain it again to me. Yet, negative. There was 1min of silence in the post office, the employees dont know what to say, Me, doesnt understand, and the customers are watching.
Here, I really felt embarrassed, I felt light headed and regretted even entering this place. I regretted even my desire of having a credit card!! Believe me people, it is really embarrassing and uncomfortable situation. I thank god I didnt have a samurai sword at that moment, or else I would have killed myself the traditional samurai way!
At that moment, I collected all my powers. I felt like all the Japanese lessons I learned for the past two years went through my head in a second. I asked her to repeat her sentence more slowly, - motto yokkori itte, onegaishimasu -. She repeated her words slowly. AAAH!! now it clicked. I swear I felt I understood everything she said. I smiled, and replied back. Then we continued throughout all the application, smoothly, with no problems.
Really, I felt like a life or death situation. But honestly, I did learn alot from this experience.
Am I willing to repeat that again? well, definitely, but not in the near future!! :)