My wife , not a US Citizen, applied for Japan visa few weeks ago @ Japan Consulate in San Francisco. We did not go on a tour nor we have any friends or relatives. We had to produce:

1. E-TIcket
2. Hotel Booking Confirmation
3. Bank Statement to prove sufficient funds
4. Day to day itinerary schedule
5. Application form

The lady at the consulate check each one of them very carefully, ensuring it all matches w/ the schedule itinerary we put in. We also paid for self-addressed-stamped USPS Express mail service (no priority mail) to mail back the passport.

One person was asked to come back later since they did not produce a bank statement to provide sufficient funds while in Japan.