That's what everyone says. The meat. But that meat could be used for anything. Curry, goulash. Same ingredient. It's the stew MIX that makes it a stew.
@Nunally Before she could think of anything the little sister called her "Wakadzukuri-senpai." That word basically means "dress to look younger," and is meant as a dig that she's Christmas Cake in high school drag.
Now it reminds me of Kako and false detective. Japanese folklore (including urban one) makes for good mystery, probably because of relatively clear set of rules.