In Japan is promiscuity looked down on?

Question:

Also, is it culturally forbidden to have premarital sex?

Answer:

I hope you will be more specific what you mean by promiscuity. It's a broad word.

>is it culturally forbidden to have premarital sex?

Haha, do you know that marriage rate is rapidly declining in Japan? A surprisingly large number of people don't get married even after 30, 40 or more.

So if it's looked down upon, very few are allowed to have sex in Japan. The bottom line is, no it's not.

Addition:
>I'm looking for a wife who is a virgin.

Oh, you want to find a virgin wife in Japan? It's like finding a four-leaf clover from millions of clovers.