Hello,
I live in Tokyo and I can speak English fluently.
I can help you with your project, but I need to know more details.
Is there a mandatory norm/quota of the number of people that I have to get to register on your platform?
Does your site have a Japanese section?
Generally, sales activity is not easy, you can't expect wonders.
What I can do is post ads in Japanese online media (SNS, community sites, etc.) but I may not be able to guarantee a certain result...