From my personal experience, there's some truth in it.

From my personal experience, there's some truth in it.
I dated two Japanese women and two Korean women. The Korean girls both prefer to stay virgin until marriage and never had penetrative sex with me.
One of the Japanese women I dated had sex with me on our second date when we weren't couple yet. The other Japanese woman was married when we were seeing each other (so it was more an affair rather than caring).
Of course this is a small sample size but the general trend is there.