A foreigner coming to Japan to teach will have a tough time using his/her teaching qualifications here in the Japanese school system, even if that person speaks Japanese. Many foreigners take the path of least resistance, which is teaching "English conversation" in private conversations schools where the requirements for work are very forgiving. As you can imagine, the pay is very low in these places. Maybe 250,000 is a typical starting salary at these places.
You might want to see if any of the international schools around the Kyoto/Osaka area have any openings. I did a quick search on the internet, which you've probably done as well, and I saw a figure of up to 7,000,000 yen for a starting salary at an accredited International School (i.e. ASIJ).