Visa Waiver Program
 

I was wondering if it is possible to come back into Japan after 90 days are over. Like going to china or korea for a weekend then coming back to get another 90 days or If I just went on a trip before my 90 days were up would I get another 90 days?

immediate response would be helpful, me and fiancee taking a trip to hong kong soon and needed to know if I would be ok. He is fine since he is a citizen here.

Technically, yes - a trip outside of Japan would allow you to have your 90 day visa renewed.

However, reality might not be so kind to you. All entry to the country is pretty much at the discretion of immigration. If they don`t like that you just popped over to some other country and came back, they are not obligated to let you in. It used to be pretty much guaranteed to work - now I am hearing more and more stories about people being denied the second visa.

I wouldn`t risk it these days.

ETA; You say you are engaged - If you have a wedding planned and proof of this, things will be much smoother.

Yes you can.
The easiest and cheapest way is going to Korea by ship. It will take just 3 hours one way to get to Busan from Fukuoka if you take the Beetle Beetle English
There is also a normal Ferry that will take longer but is cheaper and more comfortable.

When entering Korea there should not be any visa problems, but when coming back to Japan you will need a ticket going out of Japan in the next 3 months (90days).

Doing this several times in a row might work, but you could also get trouble. Once shouldn´t be a problem.

Well we do not really have any proof other than my ring. plans are still in the making. hopefully i can just do it this one time successfully because this one time is all i need. the next time i come back to japan will be as husband and wife. thanks for the advice. hope i can do this without trouble and hopefully they will listen to my fiancee since we will be traveling together.