The Red Manor is an optional location in Phantom Blade Zero, but its locked puppet door cannot be opened until late in the game. The area is tied to obtaining the game’s best ending, and opening the entrance requires a special item earned by visiting three spectral portals.
To find the manor, start at the Long Pillar Lookout bell in the Weeping Creek Valley and head north, beneath the Sha-chi Tower base. A passage is blocked by debris; lure the nearby explosive monster into it to clear the way, then take the elevator. A new bell and the Red Manor’s locked door are in the area beyond.
The first spectral portal is in Lu Village. After defeating Yuzhan, Puppet No. 3, in the well’s underground area, take the portal to a room with an inverted puppet hanging from the ceiling. The second is at the Order’s Camp, accessible after defeating Yubi, Puppet Swordsman No. 21, in the training ground. The final portal is at the bottom of the well beyond the PhanHuang Xing boss fight at the Mount of Imprisonment, facing the Inanis realm portal.
Once you have entered all three portals, go to the puppet in the center of the room. It gives you a Puppet Tongue and a Crystal Puppet Eye (Yin). Return to the Red Manor and use the tongue on the puppet serving as the door.
Inside, collect the documents, which reveal information about the Herald’s plot, then descend the well to the depths. There, you will face the Scavenger Puppet and Acolyte Hansui. Hansui joins the fight against the Scavenger Puppet, and the guide says the outcome is the same even though you cannot interact with his scarecrow. Defeating them rewards you with the Ice Mask and a Crystal Puppet Eye (Yang).
Sources: Jeuxvideo.com.