(You look around and see several dead bodies scattered across the ground.)
(Inside the leather bag is a journal and a small toy that looks like a wheel.)

(Upon opening the journal, you see a map of famous treasure sites and items--some of them have an "X" beside them, including the Silver Blade Rotan.)

(The small wheel-like toy must be the object that can summon Rotan, so you put it in your cube.)