Doorkeeper supports two ways to collect online prepayments for your event: PayPal and Stripe. While Stripe offers cheaper fees and a generally smoother prepayments, it previously only supported Visa, Mastercard, and American Express, not Japan's other major credit card, JCB.
Stripe now supports JCB along with the other credit cards. However, to enable prepayments via JCB for your community, some extra steps are required on your part. To get started, please see this article.