Experiences applying for a police criminal record certificate?

Within the next month or two I will need to apply for a police criminal record certificate (犯罪経歴証明書) for submission to an organization abroad, and was wondering if anyone here who has done this can share how their experience was, and what kind of supporting documents they brought, etc.

I was expecting that this would be a routine procedure, but recently heard from a colleague that it was like pulling teeth for them and that they were not able to convince the police to accept their application the first time they went to the station, so I am thinking of bringing a whole stack of things to serve as evidence: (i) printout and translation of organization web pages with translation which explains the application process in question and the background check documents needed (unfortunately the relevant information is spread across several pages); (ii) Japan Ministry of Justice page I found which identifies the organization and explains its functions; (iii) a generic email from the organization (and translation) addressing me by full name and stating I need criminal background certificates from all countries I've lived in in the past 5 years (was the best I could get from them since they declined to issue a letter or an email with more specific content).

It may be overkill, and I hope it is but I don't quite have anything that matches what the police website asks for, and I really don't want to take time off work to go to the police station and come up empty handed and have to try again.

For background: I recently took exams to qualify as a lawyer in England and Wales, and in addition to passing exams I need to pass background checks and whatnot (which is why I need this police certificate), which I want to get out of the way before the exam results in May.

by nyang-a-chi