Ok, its actually not a school. I've misleaded you all.

I was eating at Kopitiam yesterday in Bugis (In a mall w/ cinemas, a big Watson shop @ 2nd floor ), 2nd floor, the same with the huge Watson.
I went to the opposite building by the bridge connecting both of the buildings.
Then, I saw a group of girls dining when I was there. The uniform resembles those from Japan. The color scheme of the clothes is Grey, white sleeves. The socks are high .. Someone pardon me if I'm wrong.
So, did anyone saw these people/this school before ?