Generally very little room for bargaining in my experience for the big stores in the city eg the ones in Shinjuku like Watchnian, or Best Ishida. The range is usually very good though, and the condition generally excellent especially for modern watches. The weak yen is definitely a plus now.
You have to show your passport though at the time of purchase to get the tax waived at point of purchase. The
Visit Japan Web site gives you a QR code to get the tax waiver, and you theoretically don't need to show your passport and just need to show the QR code to get it. IRL though, most shops ask for the passport, especially for big ticket items like luxury watches. The Visit Japan site though is still useful to pre-register your immigration stuff - you then get a QR code which allows you to breeze through immigration much quicker (useful when you're landing after a long flight with tired/cranky family - trust me, I know)
I had 2 trips to Japan last year - spring and winter. Came back with a total of 3 watches
😗.. Wife rolled her eyes thrice.