[Symbol] The real "schoolbag"

Schoolbag, everyone knows what it is. We carry it to and from school since we were little, and keep enduring with it until our twenties, finally getting rid of this increasingly heavy "thing". But the "schoolbag" I'm going to talk about next should be put in quotation marks, because the one mentioned earlier is a "bag for books", while the latter is a "bag made of book covers".