Before you attempt the survival mode, there are a few preparations I recommend that you make. First, try to get your character of choice to level 50. Select a monk or shrine maid as a bodyguard and raise them to level 20, they give you items as you fight so they are extremely useful. Buy the skills Gluttony 3, Cutthroat 3, Ration 3, and Fitness 3. You also will need to customize one of your weapons. Take one of your level 3 weapons that has a bunch of stat slots and go into the shop and buy an upgrade. If you get a good stat bonus then save your game, if not then load and try again. If you happen to die, you can pay gold to start at floor 11, 21, 31, 41, or 51; whichever is your highest floor that you have reached. You need to clear a specific sequence of missions on survival mode to unlock Ranmaru Mori. On floor 1, select Ranmaru’s Request. On floor 6, select Keiji’s Request. On floor 11, select Mitsuhide’s Request. Choose whichever mission you want on floor 16. On floor 21, select Mitsuhide’s Request 2. Choose whichever mission you want on floor 26. On floor 31, select Ranmaru’s Request 2. Once you clear floor 35, you will unlock Ranmaru.