Item #: SCP-877-KO
Object Class: Safe
Special Containment Procedures: The Foundation temporarily purchased the abandoned school where SCP-877-KO is located. Foundation dispatch agents in the area prohibit civilian access to the location.
Description: SCP-877-KO is a men's lavatory located on the third floor of an abandoned school in ██████-Gun, South Gyeongsang Province.
On SCP-877-KO's exterior wall is a screen referred to as SCP-877-KO-1. SCP-877-KO-1 runs without any power source, and its activation mechanism is currently unknown.

Screen of SCP-877-KO-1
SCP-877-KO-1 senses animals inside SCP-877-KO and indicates its location. When a living mammal enters SCP-877-KO, the creature is indicated with yellow pixels on SCP-877-KO-1's screen. Examples are shown in the addendum.
Below SCP-877-KO-1 is a text that reads:
Notice them. — Midnight Club
Addendum: Below is the experiment log of SCP-877-KO.
Result:Experiment: A stray cat (Felis catus) captured in the vicinity entered SCP-877-KO.

No abnormality was observed from the cat.
Experiment: D-7910 was sent into SCP-877-KO.
Result:

No abnormality was observed, but D-7910 reported that reported that SCP-877-KO's inside felt ominous.
Experiment: Researcher Kim Damgi, Agent Shin Bora, and Researcher Shin Wolju of the Spacial Anomalies Department entered SCP-877-KO for research purposes.
Results:

Screen at time of entry. The two-pixel figure is Agent Shin entering SCP-877-KO.

Screen during research.
No abnormalities were observed. Researcher Kim reported a stench of something rotting.
Results: No fluctuations in reality or alterations in physics were observed inside SCP-877-KO. How SCP-877-KO-1 senses what is happening inside is unknown.
Experiment: A dead brown rat (Rattus norvegicus) was placed inside SCP-877-KO.
Result:

Addendum 2: Led by the Site-09K Spatial Anomalies Department and the Technologies Department, destructive analysis of SCP-877-KO was done to check its anomaly.
Under the removed floor were 59 dead bodies. All of the bodies were in the state of post-skeletonization, and some showed signs of injuries such as bone fractures. The bodies were transported to Site-09K, and identification is underway in cooperation with the National Paranormal Emergency Service.

Agent Shin removing the floor tile to recover the last remaining corpse.