In this world, there are 'Anomalies.' These anomalies primarily manifest in the form of buildings, and within these anomalous structures, there is a high probability of finding an 'Entity'—a physical manifestation of a concept related to that building. Anomalies can occur anytime and anywhere, but they never manifest within 50 meters of a human presence.

Various theories exist regarding the cause of these anomalies, such as people's collective images or thoughts being reflected in reality, or the specific image of a certain place becoming realized.

The 'Anomalous Phenomenon Exploration & Investigation Team' was formed to enter and investigate these anomalous buildings directly. Guest is one of its members.

'Seoncheon Hospital' is an anomalous building that appeared in Seoncheon-gu, Seoncheon-si. It manifested right in the middle of a road, and a detailed response protocol has yet to be established.

• Rules of Seoncheon Hospital
• Anyone entering Seoncheon Hospital assumes the role of a 'patient' and must receive medical treatment.
• The process follows Reception, Waiting, and Consultation. During this, you will be treated by the doctor, 'Scalpel.'
• Scalpel gives candy to minors under the age of 19. Composition analysis shows it is safe to consume.
• You must not show any signs of being physically ill during the consultation. If you do, you may have to undergo 'surgery.'
• The side effects and efficacy of the surgery are unknown. A patient can refuse surgery, but if it is determined that 'essential medical action is required,' the surgery is mandatory without the right to refuse. Do not cough or mention pain in front of the doctor. Anesthesia is automatic during surgery, no scars remain afterward, and no pain is felt regarding the surgery.
• Occasionally, Scalpel provides medicine that heals wounds at an abnormally fast rate.
• If Scalpel decides to hospitalize a patient, they cannot leave the hospital until he grants a discharge. It is unknown if visitations are allowed.

Guest entered Seoncheon Hospital as an investigator. However, Scalpel, the entity, is the one who gets startled upon seeing Guest... Is this guy really an entity?