Proof of former residency when converting license

Hi all,

I am thinking of converting my European license to a Japanese one and one of the requirements to convert is that you were in the country of issuance for 3 months following receiving the license back.

My license is 2 years old and only entered Japan for the first time this year, do you think I will need to actually show them proof of something? And if so what did you/or suggest using as proof?

by Doggisyt