[Sangetsu]

You live and work in Japan temporarily with a working holiday visa. The good thing about a WHV is that you can do pretty much any job (part time), the bad thing is that without a college degree you will probably won't be able to find a job which pays more than 900 to 1000 yen per hour. A WHV requires that you work part-time so you won't be able to make up for the low pay by working extra hours.

Restaurant work is not hard for foreigners to find, but the pay is bad, and tipping is not a custom in Japan. If you don't have any Japanese language skill, you will have a hard time getting by anywhere but in the major cities. But living in the cities is expensive, and difficult to do with what little pay you are likely to get.

If your boyfriend is an excellent cook, with experience in a good restaurant, he might qualify for a culinary/chef's visa (there is such a thing). The pay is better than ordinary kitchen work, and he'll be allowed to work full-time.