Have you considered capsule hotels? Super cheap (
the one I am staying at in Kyoto is $15 USD per night and
the one in Osaka is $20 and is a 5 minute walk away from the arena) but if you go to a newer one, accommodations are still totally fine. All you need to do there is sleep and shower anyway.
First Cabin's capsules are big enough to stand up in, and no more than $30 a night.
The only other major difference is sometimes (though not always), you have to check out each morning and check back in later (they can keep your luggage though). But it's not liek you have a room to keep stuff in anyway
They're perfect for shorter trips, for when you go to see a show. So you could fly to Tokyo and back from HK for like $100 USD, stay 2 nights for $30 USD, and it's totally fine for a weekend trip to see wrestling IMO
But I bet WK13 is sold out anyway right?