I've been served live abalone on a sterno heated metal plate with small glass topped dome. It's only happened once at Furofushi in Aomori, though, so I'm curious where else it might be on the menu. If that puts someone off their appetite, perhaps also be aware that I've been shown small live fish at a high end tempura restaurant by the chef. The live fish is, ahem, cooked in front of the diner and then served at the counter seat in full view of the chef. I guess looking for such a place with slightly removed table seating would be a way to get around that.

OP - I think a ryokan in Miyajima is a good call. It's been a while since I visited but a walk outside after most day tourists departed was more tranquil and a nice contrast to urban Hiroshima. I'd also hope less pricey than Kyoto options. I personally feel Kyoto high end Japanese hospitality comes off very formal. I could be wrong about that since I personally don't get much value out of Kyoto ryokans - mostly no onsens, some of the famous historical places may have very formal service (or coasting on their old reputation), and normal Kyoto lodgings already priced at a premium.

ETA KI-NRT's great review of Kinsuikan's specialty room meals https://www.flyertalk.com/forum/34884511-post56.html If you haven't seen the luxury ryokan thread and have the budget, it's a great read and resource for people who enjoy high end lodgings and dining.

I don't think it'd fit into your current trip but I'd suggest future trips from Kanazawa to Toyama to seafood lovers and then perhaps another trip to Aomori's coastline and down the Tohoku coast. Kanazawa/Toyama region has more white fishes, firefly squid, and generally a different selection of fish compared to Tokyo. You can combine it with a visit to Shirakawa Go and the Alpen route during the warmer months or over towards Nagano. Aomori coast has several large fishing ports so even the casual sushi fish is a cut above (some very average city lodging options though, due to mostly fishing industry) and popping over to Hakodate in Hokkaido for even more seafood is a delicious itinerary. Aomori has some interesting festivals if you'd be interested in that.