You have to find and take photos of all the birds in a flat. I found, and took photos of, all the birds in a flat. And some other things, some of which it seems you need to take photos of in order to unlock more birds.
I’m not sure what else there is to say about Toripon. You can get a copy here if you too want to find, and take photos of, all the birds in a flat: https://theladyvictoria.itch.io/toripon