Door locks in rural Japan & common practice re: locking your house

[littlebutfierce]

What kind of door lock would be usual for a house in rural Japan? Not a particularly grand or big or fancy house, if it matters. Would it lock automatically when the door closes, or would you have to lock it yourself? If it's not automatic, would it be common for someone to lock it right away when they come home, or would they tend to just lock it at night? Would that change if other people living in the house aren't home yet?

I'm writing a fic where two of the protagonists, who've just come home from work, get burst in on by people who mean them ill. I don't know if they would've had to break the door down or if they could just waltz right in! (I'm hoping not to have to work in something about getting the door repaired, heh.) Canon doesn't specify exact location but it is generally assumed to be in Kumamoto prefecture, in case that makes a difference.

I've been googling (in English) variants on "door locks in Japan," "door lock mechanisms in Japan," "locking doors in rural Japan," etc. Mostly I've been finding door lock companies, advice to foreigners in Tokyo to always lock your doors, things about car door locks, & the text of 2 books about Japanese architecture -- one from the 1800s & one from the 1980s, so not so useful.

Many thanks for any clarity!