Woooo! Better flow, finally here. I did that cause my internet died and couldn't work on Wata.
I don't think I can do much more for Oni at this point...
The "Best wishes!" translation is to maintain consistency with other
places where Ooishi is saying this. I think it makes sense to avoid the
literal "Happy New Year" for this line.
When I asked on the steam forum, a Japanese player was kind enough to
explain that Ryukishi07 used to use "Happy New Year" as a greeting at
his/her old workplace, and so added that quirk to Ooishi. I think it's a
fun thing, but it just doesn't make sense to me for it to be in the
English version (impossible to find this out in English afaik)
Finally found some useful reference on this
http://www.nspoliceman.com/became/post1.html
It's specifically the Second Investigation Division that handles
intellectual crime (white-collar crime) such as breeches of election
law.
Spent far too long researching this x.x