What is the best way to teach English in Japan? The good news is that there are several. Some even offer you free flight tickets!
I'm probably biased here, but I say that the best English language teaching in Japan is the Japanese government's JET program. That's how I first came to Japan. It stands for the "Japan Exchange and Teaching" Program, and although you will probably be in schools that teach English for a few hours a day, the main objective of the program is to get local people used for foreign spirits. Just imagine if your hometown had not seen any other race or culture, just on the TV. Well, that's the most of Japan. You are basically paid to be a stranger!
The JET program brings over several thousand people each year and distributes them all over Japan, from the snow north of Hokkaido to southern south Okinawa. And no, you can usually not choose where you are! Though you can choose. The government also pays for your flight.
This is a great job, but it's very much "every situation is what you do it". If you're independent, you can think about spending your time and talent and patience and talent to open your eyes, while at the same time respecting your thoughts and positions, it's the job for you.
Otherwise could you take into account direct teaching work without being responsible for "globalization." If you want to speak Japanese, do you want to learn from native Japanese speakers, would not you? And that's the same in Japan, people want to learn English from real-language. These "eikaiwa" jobs, as known, are enough in Japan. As the wages and conditions are not always great, they are sometimes referred to as "mac jobs" but if you are the kind that allows you to achieve best results, it's a great opportunity to visit an unfamiliar country, meet the people and get paid for it.
At the top of the chain is starting your own school. It's probably small I still care for you, but it always pays long-term goals!
In any case, enjoy your time here. It's a great place to live and teach English in Japan and is a great way to give something back.