Chests (9):

• Black Musk
• Dark Claws
• Lilith's kiss
• Tranquilizer
• Genji Gloves
• Kiku-Ichimonji
• Genji Shield
• Genji Helm
• Genji Armor

Hidden Item (1):

• Kotetsu

The cave has so many hidden passagways, some of them are just loop and lead to no where. 

1. You just simply follow the maps, at (1) is an injured soldier and he is about to die. Talk to him for a Kotetsu.
2. Use teleport or walk back to exit the cave.