Help trying to remember wine from Japan trip

Seven years ago, my wife and I went on our honeymoon to Japan. While we were there, we had a wine that was so amazing we still talk about it today. Sadly, because of the language barrier we never found out what it was. I’ve been trying to search for it ever since with no luck. This is honestly my last hope, so any ideas you have would be deeply appreciated. Here’s what I remember: it was served in a traditional-style restaurant in Hakone. They said it was a plum wine, though I remember it being dark red and my understanding is that plum wine is typically clear. I remember it having this very rich and sweet flavor, like a dessert wine, definitely a plum taste to it. I’m pretty sure they also said it was Chinese.

Having done some research since then, I’m almost wondering if it was some kind if red wine/plum wine blend, but I don’t know enough about wines to really say.

I’ll probably never be able to confirm exactly what it was, but if any of you could even suggest something that sounds similar, it would still be something special to share with my wife.