Shopping unpleasant in Japan

On Saturday I was wandering through an underwear shop just having a browse and I noticed that I had a shadow. Everytime I moved the shop assistant behind me would follow. This went on for a few minutes before she finally got up the courage to say, "Feel free to try anything on" and then continued to stand there, literally at my elbow, while I browsed. When I started to look for a size she was all "Do you know what size you are?" and tried to help me look, I just said "Yep." but didn't volunteer my size, just kept looking myself. This kind of thing would usually put off an over-eager shop assistant at home - but not this chick. She continued to follow me as though there was a piece of string connecting us and when I stopped in front of another display she was all "Yeah, there's none of your size in these, sorry." ARGH! Fuck OFF!! I tried to lose her by slipping behind a pillar in the middle of the crowded shop and for a moment it was successful but then she was back again, not saying anything this time - just following me like a bad smell. Eventually I said to her, "Would you mind leaving me alone?" In my most polite Japanese. She still took offence of course, but she did back off and when I did eventually try something on she was heaps quiet about it!

This is a pretty extreme example of what shopping in Japan is like. One of the first things I noticed when I very first came to Japan in high school was how shopkeepers will yell out at you as you pass by irrashaimase!!, a word without a direct English translation, but in this case seems to mean "come in and buy something". And if that was the only time they said it it would be fine, but even once you are safely inside their shop and looking around quite happily they keep saying it! The best example of this is the Daiso (100yen shop) where the shop assistants yell out at regular intervals as though they are on a timer. And if one hears another doing it, they do it too, like an automated response, or a whale searching for its pod or something. I swear, they do it so much they don't even realise they are doing it anymore. As soon as you come anywhere near them you get irrashaimased. It is SO annoying. I am already in the shop, I am already looking at the products, you saying irrashaimase in my ear constantly is not going to make me more inclined to buy something - in fact, probably the opposite is true. And a lot of times when I have gone out shopping I have come home with nothing because their constant yelling makes an already soul draining undertaking just unbearable. Sure, it saves me money, but sometimes I really do need what I set out to buy! As for following me around like a nervous child waiting for any opportunity to "help me" - just bugger off! If I want help, I will ask for it. What happened to that manner of service? That's certainly the rule I worked by in my casual jobs. Most people are quite happy to just browse alone and don't really want to forced into the awkward social situation that is small talk with a shop assistant. It's like they are all on commission or something. Mad.