Buying new released Nikon D500

I want to buy D500 which'll release the end of April. So far, I can only find them on website which required me to pre-reserve/ and they don't have the physical stores. I'm only travel 1 week in Tokyo, Kyoto and Osaka. I'm so confused why it not available in any stores. I'm worry whether I will have a chance to buy this camera.
Do you guys have any advice?

It will release on April 28, so of course right now you can only find pre-orders. Unless you really want to visit a physical store, you can preorder it and have it delivered to your hotel or to a convenience store.

http://www.amazon.co.jp/dp/B01A7ZB5EM/

It will be released on April 28. I think some retailers have it on the afternoon of April 27. If Nikon strictly controls the released date of 28th, you can't buy it until 28th.
At this moment, Bic Camera puts price of 235,650 Yen, so I think the average price will be around this. Amazon Japan puts price of 233, 270 Yen.

How come there is no fixed price? Where is can I bought the cheapest price? yodobashi ? or online? before or after release?
You mention pick up at convenient store which is quite interesting. Would it be easy to pre-order and pick up if i don't know jappanese?

How come there is no fixed price?

Because every retailer is free to set their own price.

Where is can I bought the cheapest price? yodobashi ? or online? before or after release?

I don't believe there is a magic recipe to find the cheapest prive, you just have to look around and see what you find.

You mention pick up at convenient store which is quite interesting. Would it be easy to pre-order and pick up if i don't know jappanese?

Yes, very easy, Amazon.co.jp can be used in English. By the way, if you do not have a credit card you can also pay at convenience stores in cash.

Actually it would probably be better to buy it at physical stores since then you can get it tax-free (you save about 20,000 yen). http://enjoy.taxfree.jp/

Keep in mind the new cameras are typically priced at physical retailer very close to, if not at MSRP upon release, which is about 260,000 yen for the D500. So if you get it tax free you will still likely have to pay this amount, but they will compete more on the percentage of loyalty points you can earn, which can be put toward the purchase of other items.

I would probably recommend price checking on Kakaku and then purchasing from one of those dealers, i.e. amazon in this case, which is good as they are one of the most foreign friendly online retailers:

http://kakaku.com/item/K0000843469/?lid=ksearch_kakakuitem_image

Secondary option is to find a retail store on Kakaku with a good price and go buy in person. That way you have the option to price check at a bigger retailer that can offer tax-free shopping first to see if you'll save money there.

So if you get it tax free you will still likely have to pay this amount

Isn't the list price tax included? For example on Yodobashi's website the camera lists at 259,180 tax included, so about 240,000 tax-free. That's still more expensive than Amazon; though...

Actually you're right. Looking into it more, it seems its list price of 259,200 yen does include tax, in which case MSRP is 240,000 yen is what you'd pay tax free. Map Camera, a popular retailer in Shinjuku has it for 233,280 yen tax included (10% off retail), so I'd probably try there as they do tax free shopping. If I understand it correctly you can expect a final price of around 216,000 yen.

https://www.mapcamera.com/

I don't recommend you to buy online and pick up at combini unless you are a frequent Japanese speaker.
Go to Yodobashi or Bic Camera and check the price, I don't think you have as so called point card, unlikely to happen (discount) negotiation. If you have a Japanese native speaker, take him/her to the shop and ask him/her for negotiation. Brand new camera is very hard for discount.

@tokyo friend 48 You often "don't recommend" things but rarely offer any rationale. Many non-Japanese-speakers use convenience-store delivery and are very satisfied with it.