Q: So, Touko spent all her money ordering that “Ouija Board” thing, but… what’s a Ouija Board, anyway?

Nasu: It’s a tool for communicating with spirits. By using a pendulum with the board, it supposedly allows you to magically converse with the dead. It’s similar in concept to the practice of table-turning. It was created in Victorian England (1848~1886), but you can buy them online even today. Umm… don’t actually do that, though.
Takeuchi: So did Touko actually intend to have fun trying to talk to spirits?
Nasu: Nah, she mostly just bought it because she thought it would look good in her office. Or, maybe she intends to use it as one of the 38 instant-kill weapons carried by the Mecha-Mikiya that she’s bound to make sooner or later.
Takeuchi: Touko’s pretty… unfettered, huh?

Kara no Kyoukai - Chapter 3: “Remaining Sense of Pain” Movies Q & A Pamphlets