What would be a fair commission rate for each position filled as a freelance recruiter in Japan?

I’m considering a freelance recruiting opportunity with an agency that seeks assistance in connecting with Japanese candidates. They are located outside of Japan and are looking for a recruiter to help with a Japanese client, offering a commission-only salary structure.

I would appreciate insights from anyone with experience in Japan (or even outside) on what a reasonable fee would be. I will be working on around five requisitions.

Having roughly four years of recruiting experience and being fluent in both Japanese and English, I am eager to understand how to price my services appropriately. Thank you!