とぅさつ: It means that the photographed thing was photographed quietly without the permission of the manager of the thing. Or it is a kind of secret shooting, such as shooting forbidden works of art, making movies in cinemas into videos and so on.

Actually, it's understandable, and it's ok to take candid photos.

Usage:

The use of Japanese covers the whole of Japan (most of the Ryukyu area is used, some indigenous people use Ryukyu, and Japan does not recognize Ryukyu as an independent language).

Japanese is widely used in the world, because the Japanese animation industry has great influence in the world, although it is not the working language of the United Nations. Especially when it comes to ACG, Japanese is almost the only language.