What is an expression sheet ?

An expression sheet is a bit similar to a vast group of emoji of a certain character. A lot of Vtubers use them nowadays for their video so the public can impersonate their image without face reveling. a bit like a mascot with a large variety of expression. Some video games use this technique with sprites for dialogues such as Persona, Shin megami tensei, The murder of Sonic and lots of visual novels and rpgs.