is japan a suitable place for living and work as a computer engineer? Is it expensive to live in japan?

Japan has plenty of native-born computer engineers, and the Japanese are not all that welcoming to foreigners.  You'd need a job offer to move there, and it's not likely you'd get one, not from a Japanese concern.

You might be able to get a job with a multi-national company that had an office in Japan.

Yes, Japan is quite expensive, especially housing.

Very expensive  to live there

Very hard to get a job there unless you work for a major corporation  that has offices in Japan

Japan is very expensive. Also very well educated so perhaps not that easy to immigrate to even if one is a computer engineer. 

Japan has among the world's highest cost of living. Housing is typically very scarce, very expensive, and very tiny. IF you hold advanced degrees, some sort of very specialized expertise which is in short supply in Japan, and are fluent in Japanese, you might qualify for a temporary employment visa, IF you can find a job there. 

The only country which exceeds US in average work week hours for salaried employees is, of course, Japan. They work very hard there.

Yes to all your answers. 

If you want a cheese burger it is!