What should my commission be as a freelance recruiter in Japan?

I’m about to embark on my journey as a freelance recruiter and have a potential collaboration opportunity with a recruitment agency. They’re seeking assistance for a Japanese client but struggle to connect with candidates in Japan. They are offering a commission-only pay structure.

For those who have experience in Japan (or elsewhere), I would appreciate your insights on what a fair commission rate might be. They’ve provided me with around five roles to fill.

Additionally, I have four years of recruiting experience and speak both Japanese and English fluently. Thank you for your advice!