If you are stuck on the mask puzzle solution in the Underground Laboratory during the What Lurks in the Shadows mission in Onimusha: Way of the Sword, the answer is simple: shoot the four hanging masks with your Oni Bow in the order three, four, one, two, counting from left to right. You will not find that order written anywhere inside the room itself. The clue is hidden outside, in the shadows cast through the small circular windows next to the dojo entrance, and once you read it correctly the whole puzzle takes less than a minute to finish.

This mask puzzle solution trips up a lot of players because Capcom hides the answer in plain sight instead of handing it to you directly, and it is easy to walk past the windows without noticing anything unusual on them. Bookmark this guide before you head into the laboratory, because we are going to walk through exactly where to find the puzzle, how to read the shadows, what happens if you shoot a mask out of order, and what the Unsettling Mask you win from the cage actually does once it is in your inventory.

Where to Find the Underground Laboratory Mask Puzzle

The mask puzzle shows up partway through What Lurks in the Shadows, one of the main missions on Musashi’s route through Kyoto that we cover in full in our rundown of every Onimusha Way of the Sword main mission and side quest in order. You will already have fought your way down into the Underground Laboratory by the time you reach it, and the puzzle itself sits on Level 3 of that lab, inside a dojo-style room you genuinely cannot miss. Walk in and a short cutscene plays where four masks drop down from the ceiling on chains, hanging at roughly head height in a straight row facing the door.

Nothing inside that room tells you what to do with the masks, and that is exactly the trick the game is playing on you. A lot of players draw their bow immediately and start shooting in the order the masks happen to be facing them, which almost never works. Before you fire a single arrow, back out through the door you just came in through. The real mask puzzle solution is waiting for you outside, not inside.

The dojo room fits the tone of the rest of the Underground Laboratory, dim, quiet, and built with just enough dread that you half expect something to jump out while you are lining up shots. Nothing attacks you during this particular puzzle, so you can take your time, but it is worth clearing any nearby enemies in the corridor before you commit to the room so you are not interrupted mid sequence.

How to Read the Mask Puzzle Solution Clues

Once you are back outside the dojo room, look at the small circular windows built into the wall on either side of the entrance. Four more masks sit behind that glass, and each one casts a shadow with a different number of openings cut into the surface. On the right side of the entrance, the mask closest to you has one opening cut into it, and the mask further along toward the wall has two. On the left side, the mask nearer the wall has three openings, and the one closer to the entrance has four. That count of openings, one, two, three, four, is the entire mask puzzle solution, and it maps directly onto the four hanging masks inside the room.

Here’s a little tip: take a moment to actually count the holes rather than eyeballing them, since one and two look similar from a distance and it is easy to mix them up in low light. The game does not gate your progress on getting this exactly right the first time, so there is no harm in stepping back inside and outside a couple of times to double check before you commit to shooting.

The Correct Mask Shooting Order in the Underground Laboratory

Once you have matched every shadow to its hole count, walk back inside and face the four hanging masks head on. Number them one through four from left to right, the same way you numbered the shadows outside, then draw your Oni Bow and shoot mask three first, then mask four, then mask one, and finish on mask two. That three, four, one, two sequence is the full mask puzzle solution for this room, and it is the same skill you already used with the Oni Bow when you had to sever the tether cord to end the Rasho-gan fight, just aimed at a set of stationary targets instead of a boss.

Each mask that gets hit in the right position locks into place with a short chime, so you will know instantly if a shot registered correctly. Take your time lining up each shot rather than rushing through the sequence, since the masks are close together and it is easy to clip the wrong one if you are firing too quickly. Standing a few steps back from the row before you draw the bow gives you a cleaner line of sight on all four masks at once, which makes it much easier to track which ones you have already hit.

What Happens If You Shoot a Mask Out of Order

There is no penalty and no timer attached to this puzzle, so do not stress about getting the order wrong on your first attempt. If you shoot a mask out of sequence, nothing resets and nothing punishes you, you simply step back outside, recheck the shadows through the windows, and try again with the correct three, four, one, two order.

Everything you need to solve it is already in the room with you, which makes this one of the more forgiving environmental puzzles in the game compared to some of the timed encounters elsewhere in the Underground Laboratory. If you genuinely lose track of which masks you have already hit, that is fine too, since the ones you shot correctly stay locked in place while you go back and forth checking the windows, so you are never starting completely from scratch.

What You Get for Solving the Mask Puzzle: The Unsettling Mask

Once all four masks are shot in the correct order, they are pulled upward into the ceiling and a nearby cage swings open, revealing the Unsettling Mask sitting inside. Pick it up and carry it back to the locked door you passed earlier in the Underground Laboratory, the one with a carved face mechanism built into its center. Slot the Unsettling Mask into that mechanism and the door’s eyes glow red before it grinds open, letting you continue deeper into the lab toward the rest of the What Lurks in the Shadows mission.

Clearing this mission does more than open one door, too. What Lurks in the Shadows is also the mission that flips the switch on the game’s Lion Dog collectibles, so once you finish it, Lion Dog pawprint icons start appearing on your map across Kyoto for the first time. If you are chasing the Mooncrossed or Kikoku blade skins later on, solving this mask puzzle solution properly and pushing through the mission is a required step, not just a nice detour. The habit of reading environmental clues before you start shooting will come in handy again too, whether that is picking apart the shadow clues here or timing a shot on the puff-up window during the Kubi Akari swarm in Pale Lights in a Night Sky.

Mask Puzzle Solution FAQ

What is the correct order for the mask puzzle in Onimusha Way of the Sword?

Shoot the four hanging masks with your Oni Bow in the order three, four, one, two, counting the masks from left to right as you face them.

Where do I find the mask puzzle solution clues?

Step outside the dojo room where the masks are hanging and look through the circular windows next to the entrance. The shadows cast by the masks behind the glass show one, two, three, and four openings, and that count gives you the shooting order.

What does the Unsettling Mask do?

The Unsettling Mask is the reward for solving the puzzle. Carry it to the locked door you passed earlier in the Underground Laboratory and slot it into the face mechanism carved into the door to open it.

Is there a penalty for shooting the masks in the wrong order?

No. There is no timer and no penalty, so you can step back outside to recheck the shadows and try again as many times as you need.

What mission is the mask puzzle in?

It is part of What Lurks in the Shadows, one of the main missions in Onimusha: Way of the Sword, found inside the Underground Laboratory on Level 3.

That covers the full mask puzzle solution for the Underground Laboratory, from finding the shadow clues to using the Unsettling Mask on the door beyond it. If shooting things in the right order is turning out to be your strong suit, that same precision with the Oni Bow is worth practicing before you reach Ifuu’s floating attack in Windswept Kennin-ji, where interrupting him with a well-placed shot saves you from eating one of his hardest hits. Check out our other guides on ingametor.com for more Onimusha: Way of the Sword walkthroughs as you make your way through Kyoto.