Tokyo for SET Lovers

I’ll be in Tokyo next month and will probably have a week of free time. I’m familiar with Akihabara, but I’ve mostly bought cartridges and records during previous Japan trips. This time, I’m interested in shopping specifically for tubes and, if possible/realistic via a translation app, SET amps. Where should I go?

At the moment, I’m planning to go to Sun Audio because I’m interested in their 300B amps, but beyond that I’m open to any suggestions/recommendations. In general, I’d like to focus on the boutique designers over the usual mainstream brands (Accuphase, Luxman, etc.).

Thanks for your help