If you take a Japanese teacher out to lunch, should you expect to be rewarded?

Question:

Is it Japanese culture that if you treat your teacher to something or give them a gift, they say "thank you" by boosting your grade up a little?

Answer:

You never know.

I know the correct answer is "no," and that is what I'm supposed to say. But as most things in life, it depends on the person.
Common,simple Japanese people are not generally dishonest or really into corruption, but politicians are filthy dirty, as well as many business leaders. Any elite group in Japan is pretty well rotten. The LDP, Sumo, the business world, the media, who crucify a snowboarder who doesn't tuck in his shirt, but let TEPCO--the nuclear clusterfvck people-off the hook. They are all despicable and the Japanese people deserve something better, but will never get it since they never demand. I think because most common people are generally good-natured, they are easy to take advantage of, so the people who rise to the top are those who exploit the kindness of others.
So maybe so. But don't count on it.

You seem like the kind of worm who is going to go places in life. By cheating and lying. way to go.