The foreign nationals with nationality not described in following link, have to get Japanese Visa even to stay for short term, like a few days.
To enter Japan with this temporary visitor visa, a foreign national need a Japanese citizen or a Japanese resident foreigner or some Japanese legal entity, who sponsors and invites him/her to Japan.
If you can and want to invite foreigner, the following documents are required by Japanese embassy or consulate.
1. document explaining the reason of the invitation
2. plan during the stay
3. letter of guarantee
After making these documents, you send them to the invitee, and the invitee
files it to the Japanese embassy or consulate near to him/her.
We can make these documents on behalf of you.
But you need to find your sponsor by yourself.