Cell coverage/eSIM in Yakushima?

Has anyone traveled to Yakushima with a tourist eSIM and can say what the coverage was like and what provider worked? The most recommended tourist eSIM I'm seeing for Japan is Ubigi, which says it uses the KDDI and Docomo cell networks. And the Yakushima tourism site says Docomo is one of two service providers on the island. So I think this combination will work, but was hoping for someone with specific recent experience that can say what worked for them.