Naturalization 5 year (student visa)?

I've read that time spent in Japan on a student visa doesn't count towards the 5 year requirement for naturalization. I've also read the opposite from different sources.

Which is correct? Can I naturalize with 4 years on a student visa and 2 years on a work visa?

I would say no (to your last question), because what immigration authorities look for is whether you definitely has your base of your living in Japan, AND have the intention of staying for good in Japan.

all valid continuous 在留資格 (zairyū shikaku) status of Residence count, even ones that do not permit work (such as a some student and spouse statuses).

the odds of someone straight out of school qualifying for the other part of naturalization requirement (Livelihood requirement) is low. For both the applicant's benefit and Japan's benefit (and this Immigration Service's benefit: it apparently doesn't want to take the money from people whose chances of acceptance isn't near 100%), the Ministry of Justice does not want people that link themselves formerly and exclusively to the state to have a high chance of falling into poverty and living on welfare. With all due respect to students (everybody was one once upon a time), most haven't shown they can fend for themselves in the real world off campus for many years, in earnings and/or stable employment.

If you are a student and you come from exceptional circumstances — in other words, you're rich, you can prove it, and you can demonstrate that you can comfortably live in Japan for the foreseeable future without worry — I wouldn't let the fact that part of your Status of Residence was as a student stop you from applying. I would, however, caution you that naturalization is a bigger commitment and can be more permanent than marriage; you should think about the ramifications of naturalizing young the same way as people who caution those considering young marriage.

The Naturalization process takes more than just declaring your eagerness to become a Japanese national.

answer to your question is : NO
5years on work visa ,
is safe to be on PR before naturalizing.
you most have been paying your tax, health insurance, and pension
most have a steady income ... you need to be like shin in your company or if own your company .need 2years steady income.

2 years working seems short, but as you say there's conflicting information floating around. Just go your nearest regional affairs bureau and ask them.

-this says student visa doesn't count
https://www.tokyoimmigration.jp/?p=178
-this says student visa does count
turning-japanese.info
-the most official source doesn't mention student visa at all
http://www.moj.go.jp/ENGLISH/information/tnl-01.html

Maybe talk to a lawyer?

Hi, Let me answer your query, The Japanese lawyer explains in this video. The answer for your query is given in this video. He say you must have more than 3 years work experience on proper work visa.
If you are student for 5 year and worked for 2 years. And total is 7 years in Japan. The person is not eligible.
https://www.youtube.com/watch?v=OWgVH1Amhpw

in regards to the video that guest55 linked
https://www.youtube.com/watch?v=OWgVH1Amhpw

At 6min20 he says that you are eligible with 4 year student visa and 3 year work visa (so 2 years of your student visa would count towards the 5 year total).

Here is a summary of what he said:

Case 1:
If you live in Japan continuously for five years:
In this five years, you fulfilled the requirement:
2 years as a student
3 years under working visa as a regular worker (正社員Cshain）NOT ARUBAITO OR PATO
It is OK to apply. He did not say you will be accepted though.

Case 2:
spending 7 years in Japan.
5 years as a student.
2 years under working visa working as regular worker (正社員Cshain）NOT ARUBAITO OR PATO
This is NOT OK to apply.

Case 3:
7 years in Japan:
study 5 years
worked 3 years under working visa working as regular worker (正社員Cshain）NOT ARUBAITO OR PATO
This is OK to apply.

The official source says:
(4) that he or she is able to secure a livelihood by one's own property or ability, or those of one's spouse or other relatives with whom one lives on common living expenses;

So, being a student automatically tells them that you do not fulfill the requirement. Students cannot support themselves even if you do arubaito. Students need someone to support them. Being a student is not counted unless the person works continuously for 3 years under working visa working as regular worker (正社員Cshain). This is the lawyer statement. Where did he get it? is written somewhere that we do not know? Is the lawyer simply saying that to call people to use his service?

As far as I know, students years do not count and should not count unless the person is a highly skilled where the ministry of justice leans the process. If you are poor or there is the risk that the government may give you any sorts of social support, your application will be denied even after applying.
sorry for any typos.