Used bike registration process

Hello a fellow study abroad student who just returned to the states has given me his bike key(his bike is in Japan, another friend is watching over it for the time being) since he's done studying in Japan and won't ever be back.

What is the process I have to go through to get this bike to register to my name so that the police won't stop me and take me in? Will I need any extra information from my friend to officially hand over his bike to me now?

When I inquired the police a couple of years ago, they told me that the former owner should write a note mentioning who is giving the bike to whom. The new owner should then bring the note, bike and probably an ID to his/her nearest koban and the policeman will re-do the registeration. I remember writing the date and reference number of the bike and handing it to the new owner who was a Chinese student, and never heard of him having any problems about it.

You should phone or visit your nearest koban or police department to up-date yourself and see if you really need to have your friend fax a note for you from overseas.