We had to cut Niigata out of our trip. Are there any koi farms open to tours closer to Tokyo?

I'm a fish nerd, and absolutely love koi, so Niigata was high on my list to visit, but it just doesn't work with our itinerary. I know you can see koi at plenty of different places, but the farming side of things are what makes nishikigoi so interesting to me. Are there any farms that offer tours outside of Niigata?