Do I need a round trip ticket to Japan with a work Visa?

Question:

I am an American with a valid work visa for Japan but I can not find any information on if I need a round trip ticket or not.
I know that those entering the country with no visa/student visa need one, but what about work visa?
Thank you!

Answer:

ALL foreigners, regardless of which Visa they carry, are required to present return airfare documentation to the Immigration officials when traveling TO Japan.
The date of return doesn't matter as long as it is a return ticket.
This is a measure to keep illegal foreign immigrants to a minimum.