Complex sentence: Lan Di demands Iwao gives him the dragon mirror, a mysterious stone artifact; after he threatens to kill Ryo, Iwao tells him the mirror is buried under the cherry blossom tree outside.
Split into simpler sentences: Lan Di demands Iwao give him the dragon mirror, a mysterious stone artifact. When he threatens to kill Ryo, Iwao tells him the mirror is buried under the cherry blossom tree outside.