Arent japanese sizes different from american sizes?
 

I mean dont they run smaller?I was trying to explain to this girl
that shoe sizes and clothes
even bras run smaller in japan but she refused to listen to me
because she thought I was lying when I said even the smallest size
in this asian brand was too big for me(im at a low weight)
I also told her because im a size 8 in shoes finding shoes in japan
would be pretty difficult for me
she went on to tell me im a liar because she goes to china once a year

so now im confused...
do japanese sizes run smaller than american sizes or no?

In terms of what is available, I would say yes, available sizes run smaller in Japan.

However, for a male, a size 8 shoe is 26cm in Japan. That is always readily available.

As I understand bra cup sizes are scaled differently in Japan (just like shoes).

The Large size in Japan is probably going to be comparable to the American Medium in terms of a male shirt, from my experience.

There is a fair difference. Back before vanity sizing changed US sizes (10+ years ago the size standards were different), a US M was a Japanese L. Now it seems that a US M is a Japanese LL or even 3L.
Even measurement based clothes have been hit by the vanity thing. When pants in Japan say they have a waist measurement of so many cm, they have a waist measurement of so many cm. Apparently US brands give somewhere between 3 and 5 extra inches over the listed size. US shoe sizes also tend to be what would be called a 3EEE in Japan - designed for wider thicker feet... So what is a size 8 in the US would be more like a size 27 3EEE (virtually impossible to find in normal stores.)
My husband can wear size 8 US shoes quite comfortably, but we have to hunt up and down for 27.5 3EEE shoes to fit him.
Bra sizes are on a different scale altogether and are designed for a different shape of chest, in my experience.

Regardless though, I find it hard to imagine that someone couldn`t find clothes small enough in Japan.

My shoe size is 29 to 29.5 depending on the shoe. Not easy to find that size here in Japan I can tell you!

I actually have a shirt that lists its size in various countries (for some reason)

It is a US Medium, a UK Medium, a AU Medium, and a Japanese XL ;)

Also I wear size 12 Men shoes, so I didn't even bother looking at shoes while in Japan!

well we were talking about this asian store here in america
and i said they probably used american sizing
then she went on to tell me that clothes from asia are the same sizes
they are here
and some how the convo drifted into japanese sizes