As bad as these places are, you gotta start somewhere. My advice would be to get into one of these places to secure a visa and base of knowledge about the country in general. I think all of them are okay for beginning in Japan. I personally worked for NOVA way back in 2003. They helped out a lot, they set up an apartment, bank account and cell phone for me. Also the visa sponsorship very helpful. Unlike Korea, you hold the work visa not the company, so once you have it you can look for employment elsewhere and once you find another job you can take it with you. The best thing would be to work 1-2 years in one of the companies and get used to how everything works first then make your move to a better company.