The best thing to do is contact the Japanese consulate and ask if you fullfill the conditions of any long term visa.
A quick search, however, reveals one that may suit your purpose:
Designated activities (Long Stay for sightseeing and recreation)
6 months, renewable up to 12 months
The linked page describes the further financial and health insurance ...
What I would do is ask the station staff manning the gate at Kurashiki, explain that you are going to Izumoshi and show your pass. It is likely he can issue you a ticket that will take you all the way to Izumoshi and ask for the fare difference between Soja and Izumoshi. I'm pretty sure the staff are used to cases like yours.
Of course, you could exit Soja ...
As TIMATIC states, you're not allowed to enter, nothing more nothing less.
Unlike Narita, Haneda's transit zone is open overnight, hence TIMATIC saying transit for up to 72 hours is possible there.
As such, provided your trip is on a single ticket, you can transit.
You may also consider buying the Sanyo-San'in Area Pass instead.
It's ¥5,700 more expensive, but in return:
2 more days of validity, i.e. 7 days in total
Izumoshi is included in the area
Seat reservations without additional fares
The fare of a single, one-way, non-reservation seats, limited express train from Soja to Izumoshi is ¥5,610. It appears that the ...
I would suggest that this is a total exclusion on travel and omissions are errors and not intentional omissions, given that the list for prohibited countries is pretty darn complete - but the thing which sealed it for me is that countries where COVID-19 is eliminated from the population-at-large is on that list, for example New Zealand.
I can also find no ...
I think the answer is actually "yes, because you can't use your pass for the limited express".
If you are going to Izumoshi, then you will be travelling on the Hakubi Line, and use the Limited Express "Yakumo". However, the page of the Kansai-Hiroshima Area Pass says that the limited express trains covered are:
Non-reserved seats on ...
Daisetsuzan National Park is open. Sounkyo Visitor Center have staff.
The Sounkyo Visitor Center is the core educational facility for Daisetsuzan National Park. Information about local wildlife is on display through video panels, a 3-D topographical diorama of the park, and taxidermy mounts of Hokkaido wildlife. There is a lounge space and a craft corner ...