Let's try that again....
OP, I hope you don't mind if I offer you some friendly advice regarding your plans. It seems that you may have limited experience with women and Japanese culture, and it seems you haven't had the opportunity to visit Japan before. Considering these factors, it's important to consider the potential challenges that lie ahead. Engaging in compensated intimate experiences, in a foreign country where you are unfamiliar with the language and culture, as your first experience may not be the wisest decision.
Instead, I would like to suggest an alternative approach that could lead to a more positive outcome. There are websites like Arrangements where you can connect with independent providers local to you who may be understanding of your situation. They likely have encountered similar circumstances before, so communication would be more feasible. Additionally, taking the time to study basic Japanese could prove beneficial during your stay. With a month or more ahead, you could learn some essential phrases and gain a better understanding of the language in addition to getting some sexual experience under your belt, so to speak.
Furthermore, I'd like to emphasize the importance of your well-being. If you're experiencing concerns about your sexual performance, it might be helpful to consult a medical professional regarding generic ED medications such as sildenafil or tadalafil. Experimenting with them beforehand, within the comfort of your home, and engaging with a few understanding partners could build your confidence before venturing abroad.
Please understand that I'm only trying to help you avoid any potential challenges or discomfort you may encounter. It's crucial to approach these matters with thoughtfulness and care.
(In case it's not obvious, I just rewrote Keihan's post - but nicely.)