In my experience you won't have any problems buying anything except some of the more limited editions. No waitlists. I usually stick to big discount department stores like Bic Camera, which are official ADs but offer good discounts (maybe 20%), plus some extra (5%) discount sometimes if you use Visa card, etc. You'll get tax knocked off too, at time of purchase. Don't bother asking for discounts, it's not a thing in Japan.
Try and figure out what model(s) you want before you go to avoid being overwhelmed by choice, but be prepared for an impulse buy as it's all very tempting. You might consider getting a Japan Domestic Market (JDM) piece that's only available in Japan. Yen is so weak now, you're virtually sure to bag a bargain anyway.
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