Individual regional immigration offices and the individual clerks at them have pretty substantial latitude with regards to how they interpret the regulations. Another similar issue is how much salary you need to have to "self-sponsor" one of the professional visas (which is a thing which isn't really anticipated in the written regulations per se but can be finangled out of Immigration). The amount can, depending on the whims of the examining clerk, be "3 million yen", "300k yen per month", "at least as much as a Japanese person in your line of work", "enough to not be a burden on the public purse", "at or above the average income in this prefecture", etc.
(I will pause to say that if you'd trust an HN comment over the advice of your lawyer it is time to get a new lawyer.)
This flexibility can be a blessing or a curse. Usually it's the latter.
A good immigration lawyer should know the ins and outs of your local immigration office and be able to tell you fairly confidently (not 100%) what will and won't work.
My lawyer... is very japanese-esque inflexible. No other lawyer (or friends that recently acquired the same visa) mentioned this new requirement; but the lawyer refuses to check with the immigration office.
(I will pause to say that if you'd trust an HN comment over the advice of your lawyer it is time to get a new lawyer.)