Hanging items on walls at home

Hello 👋

I’m curious if anyone knows what building material walls are typically made from, and if you have experience hanging items on the walls?

Nothing too heavy: small shelves, decorative items, etc.

I recently bought a new-build house here in Osaka and unlike the house I had back in Canada, I really have no clue what’s behind these walls.

I would have used a stud finder and wood screws, or drywall anchors, but before I drill here, I want to know what I’m drilling into.

Thanks!