I recommended avoiding IMO Talent Agency due to my extremely frustrating past experience with them, but are there any good talent agencies for us foreigners here in Tokyo? I compiled a brief list:
A friend's recommendation, I only recently registered with Avocado, so I haven't yet received any job offers. However, I've heard from many others that they're professionally-run and respectable. In fact, I believe they're run by foreigners frustrated by the questionable business practices of other talent agencies. The registration process was very well-explained, clear, and professional.
DAG Music is a talent agency primarily for musicians. As part of the registration process, I recorded and sent them a demo medley, including clips from my original songs. Unfortunately, I didn't receive any job offers from them...LOL. I guess they didn't like my stuff...so sad. Nevertheless, like the others, I was referred to them on the advice of fellow foreigners.
Ask others about the above agencies, and you'll likely hear positive things. I can't stress this enough--it's critically important to vet and validate when working in this under-regulated industry. Best of luck to you, fellow foreigner!
I've compiled a far more comprehensive list of talent agencies for foreigners in the Mondaiji Directory. Feedback regarding your own experiences with them is very welcome and encouraged, so please feel free to leave comments in the directory.