How to Open the Locked Cave Doors at Mount Oe in Onimusha: Way of the Sword

TL;DR

• The locked cave doors at Mount Oe cannot be forced open — you need the Dungeon Key.
• The Dungeon Key is earned during The Demon on the Mount quest.
• To get it, find alternate crawl-through routes in the cave, reach the trapped villager, and defeat three Genma.
• After the fight, the rescued man hands Musashi the key as a reward.
• The Dungeon Key is reusable — it opens all locked cave doors in the area.

How to Open the Locked Cave Doors at Mount Oe in Onimusha: Way of the Sword is one of the first things players get stuck on during this mission. When you enter the caves, you will run into several locked doors right away. The objective marker points toward a trapped villager, but the doors make it impossible to walk straight to him. The game does not tell you what to do next. This guide explains everything — how to reach the villager, what to fight, and how to get the Dungeon Key that opens all those locked doors.

If you are also struggling with other parts of the game, check out our guide on Onimusha: Way of the Sword tips and tricks for beginners for a solid foundation. And if you already reached the boss at the end of this mission, our guide on how to beat Shuten Doji at Mount Oe will help you through it.

How to Open the Locked Cave Doors at Mount Oe in Onimusha Way of the Sword

Where Are the Locked Cave Doors at Mount Oe?

The locked cave doors show up during The Demon on the Mount quest. This is the main mission that takes Musashi to Mount Oe. The caves here are large and spread across multiple sections. Several doors are sealed shut with no obvious way to open them. The objective marker can make it look like the villager is right on the other side, which makes it even more confusing.

The key thing to understand is this: you cannot force these doors open. Hitting them does nothing. You need a specific key item, and you have to earn it first.

How to Get Past the Locked Doors Without a Key

Before you have the Dungeon Key, the only way forward is to look for alternate routes. When you reach one of the locked cave doors and cannot go through, look around the cave wall nearby. There is a small hole that Musashi can crawl through. Get into the opening and follow the passage to the other side.

These crawl-through openings are the game’s way of telling you to go around rather than through. Once you squeeze through one of these gaps, you will be able to hear a man shouting. Looking through the barred doors from this new angle, you can see a man being dragged away by Genma. The villager is close — but there is still another locked door between Musashi and the enemies holding him.

How to Rescue the Villager and Get the Dungeon Key

Once you locate the villager, you need to fight your way through to him. Here is the step-by-step breakdown:

1. Follow the alternate cave passages. Use the crawl-through holes in the cave walls to bypass each locked door. The game will route you around them if you explore carefully.
2. Reach the villager’s location. After navigating through the passages, you will find the man surrounded by Genma who are threatening him.
3. Defeat the three Genma. Fight all three enemies in the area. Drain their health and collect the souls they drop. This is a good chance to use any Oni Armament you have available, like the Flashing Void, if it is charged up. Once all three are dead, the immediate danger to the villager is over.
4. Watch the cutscene. After the fight, a short cutscene plays. The rescued man thanks Musashi and explains that he managed to steal a key from one of the Genma during the chaos.
5. Receive the Dungeon Key. The man hands the key to Musashi. This is the item you need to open all the locked cave doors at Mount Oe.

How to Use the Dungeon Key

Once you have the Dungeon Key, using it is simple. Walk up to any locked cave door and interact with it. The door will open. There is no trick to it — just approach and press the interact button.

The important thing to know is that the Dungeon Key is reusable. You do not spend it or lose it after one use. This means you can go back to any locked door you passed earlier and open it. Some of those doors lead to optional areas, chests, and shortcuts worth checking out.

One of the main uses of the key after the villager rescue is to unlock the door on the walkway below, which leads further into the cave section filled with Malice. You will need to navigate carefully in there — spiders are lurking, and you should use Oni Vision to spot hidden enemies before they spot you.

What Comes Next in The Demon on the Mount Quest

After you rescue the villager and get the Dungeon Key, the quest continues. The next objective is to head after the Monk. This takes Musashi deeper into the Mount Oe area and eventually into the castle itself. The path from here involves:

• Navigating a Malice-filled cave using the Dungeon Key on locked doors.
• Using levers to reposition cages and cross gaps with Oni Agility.
• Shooting explosive barrels to blow open blocked gates.
• Facing multiple enemy waves including armored Genma mini-bosses and Oboro Garasu.
• Eventually reaching the castle and confronting the chapter’s main boss.

For a detailed look at the cave’s lever and cage puzzles, the Maxroll walkthrough for this mission breaks down the full path with maps. It is worth using if the cave layout is giving you trouble.

Tips for the Mount Oe Cave Section

Here are a few things that will make the cave section at Mount Oe easier:

• Use Oni Vision constantly. Spiders hide inside sealed doors and on cage walls. If you approach without revealing them, they will get a free hit on you. Always scan the area before walking into a new room.
• Kill spiders with the bow. Many of the spiders in this section are perched above or across gaps. You cannot reach them with your sword. Use the Oni Bow to shoot them from a distance.
• Watch for Malice zones. Several sections of the cave are filled with Malice fog. Moving through it drains your health unless you clear the Malice Plants first. Check out our Malice fog guide if you are unsure how the mechanic works.
• Save at every Spirit Mirror. The cave is long and dense with enemies. Every time you see a Spirit Mirror, use it. You do not want to redo large sections if you die. For more on how Spirit Mirrors work as save points and fast travel, see our Spirit Mirrors guide.
• Use Flashing Void on armored mini-bosses. The Oni Armament found earlier in the level, the Flashing Void, is especially effective against the armored Genma mini-bosses in this area. If your Oni Power is charged, do not hold back.
• Check for optional rescue NPCs. During the castle section that follows the cave, there are optional villagers you can rescue. They are not required, but saving them can reward you with useful items. Look out for them as you move through each area.

Is the Dungeon Key Related to the Locked Door Chest in the Cave?

This is a common point of confusion. There are actually two different locked door puzzles involving caves in this game, and they are not the same thing.

The Mount Oe cave locked doors are opened with the Dungeon Key you get from rescuing the villager. That is what this guide covers.

There is a separate locked door puzzle in the Oni Refuge cave, which takes place during The Stage Is Set at Kiyomizu quest. That puzzle involves using the Oni Bow to shoot a locking mechanism through a broken window from the back of the room. You can find full details in our guide on how to get the chest behind the locked door in the cave.

If you are looking for the chest and not the Mount Oe quest doors, make sure you are in the right part of the game first.

What Happens If You Skip the Villager Rescue?

You cannot permanently skip it. The Dungeon Key is required to continue through the cave and reach the castle. Without it, you will eventually hit a locked door with no crawl-through hole nearby, and there will be no way forward. The game forces you to complete the rescue as part of the main quest progression.

However, you do not have to rescue every optional NPC in the castle section that follows. Some rescues are optional and simply reward you with loot. The villager who gives you the Dungeon Key is the one you must save — the others are your choice.

How to Beat the Final Boss at Mount Oe

After you clear the caves and make your way through the castle, the mission ends with a major boss fight against Shuten Doji, the Oni lord of Mount Oe. This is one of the longest and toughest fights in the game up to this point. It is a multi-phase battle with escalating speed and aggression in each phase.

A few quick tips for this fight:

• The Oni Bow can interrupt Shuten Doji’s fire breath attack. Shoot him the moment he draws breath to cancel it.
• Keep your Oni Power saved for his enraged phases when his attacks speed up and become harder to parry.
• Watch the blood meter — understanding the boss blood mechanic can help you time your most damaging moves.

For a full breakdown of every phase and attack, see our complete Shuten Doji boss guide.

If you want to see how this boss compares to others in the game, take a look at our full Onimusha: Way of the Sword all bosses list.

Onimusha: Way of the Sword is available now on PC via Steam, PlayStation 5, and Xbox Series X/S. More information about the game can also be found on the official Capcom website.