All they really care about is that you have a tourist stamp on your passport (temporary admittance, the length of which varies depending on your country of origin), not a working visa or other form of legal long-term residence.

The form itself is not complicated. If you want to avoid waiting, pay cash or credit card for your transport into Tokyo and validate your pass the next day at any station that has a Midori-no-Madoguchi (ticket office indicated by a green four-leaf clover sign).