My parents are coming to Japan in May, so we're looking at somewhere
for 2 weeks in Osaka at a reasonable price - probably business hotel,
or maybe even a weekly mansion.

However, looking at a few Japanese hotel aggregators, all of them only
allow booking 3 months in advance and/or stays of 7 or 8 days max.
Even going direct to hotels, they seem to have the same conditions.

Compared with us trying to book a holiday in June in Germany, Austria
and France, where we booked everything in one afternoon, with almost
all the hotels having online booking systems that work properly (and
in English), it's a real pain in the bum.

Am I going to have to resort to a real travel agent and hope they have
decent discounts for slightly longer stays?

Ken