armchair psychologist here
made an account to say this - it's likely that masao is not traditionally mentally ill(eg. autism, schizophrenia, what have you).
from what i've gathered he's a wealthy alcoholic and for a time used the hoarder house to go on drinking binges - this evidently lead to toilet steaks.
him hiding his very presence at said house and generally being drunk lead to the trash pile. he clearly has no issue throwing it away and is seen doing so in one video. he's aware of his mess, thinks it's funny, and doesn't care if it goes away. he even gets dressed up in a costume to do it, a level of awareness rarely seen by hoarders( there's an episode of hoarders where one shits in a bucket then goes and makes food, they're usually either unaware of the mess or unaware that it's bad)
he's always had two houses, we're just seeing the new house in his later videos. keep in mind that everything in the mess-house is very old - it's like he only has things to cook and drink there and is letting the house itself rot. my conclusion: Masao is a true eccentric, an alcoholic, and not a schizophrenic, sperg, or typical hoarder.
