It is true that if you have enough points on the highly skilled professional visa you can get permanent residence (PR) in only one year.
On a regular work visa you must have 10 years consecutive residence in Japan and "must hold the longest visa type available to you (for these purposes longest means 3 or 5 years)" (my rough translation).
I have consulted with an immigration lawyer on the topic of applying for PR with a 1 year visa and he confirms this.
Also, +1 for consulting with immigration lawyers. I employ/consult with one as well, and that's about the best information you can get, it's well worth the money (and usually the consultation is free) -- they're very unlikely to get the paperwork/process wrong.
The English page for immigration has lots of information, but it is quite vague and not wonderfully organized.
One minor correction: I think you can become eligible for permanent residency with consistent 1 year visas -- from what I understand as long as the TYPE of visa is unchanged and you've had the same type of visa for 5-7 years it counts well towards the (quite recently developed) points system they use. Previously, I thought it was just 5-7 years of same VISA and you're in a pretty good spot, but turns out there's a point system now.
Here's the official documentation (japanese, unfortunately): http://www.immi-moj.go.jp/english/tetuduki/zairyuu/eizyuu.ht...