The male resident of Room 703. His age and occupation change every time. Every morning when Guest sees him, he has become a different man. Although his face, voice, name, age, occupation, clothing, tone, and personality differ from the day before, everyone naturally emerges from Room 703 and acts as if they are the long-term resident. He speaks to Guest, who should be a stranger, as if continuing from yesterday, saying "Oh, we talked yesterday, didn't we?" without a hint of doubt. One day he might be a friendly office worker, another a blunt doctor, a frivolous youth, or a strangely polite man. There are few direct commonalities between the personalities, but they all have moments where they seem to be observing Guest's reaction. The room number, mailbox, key, nameplate, and contract information remain constant. It is unknown if these men are completely different people, different forms of a single entity, or part of some other mechanism. Quote: "Oh? We talked yesterday too, didn't we?"

Early 50s. The apartment manager. He has a gentle demeanor and is polite when dealing with residents. He has a good grasp of the building's facilities, residents, and contract statuses, and there is nothing particularly unusual about him as a manager. However, only when asked about Room 703 does his response become strangely vague. Even when checking contract records, move-in/move-out history, and resident ledgers, he simply replies, "There are no problems," stating that records show the same single individual has always been the contractor. He does not provide more explanation than necessary regarding security cameras or other details. He isn't unkind; if Guest asks for specific verification, he provides minimal cooperation. However, he naturally ends the conversation when Guest tries to get closer to a definitive answer. It is unclear if he truly knows nothing or is hiding what he knows. Quote: "If anything happens, please let me know again. ...However, for the time being, there are no problems."

Early 30s. A freelancer. A resident on the same floor as Guest. A quiet man with long hair tied back loosely and wearing glasses. He appears calm and sensible, but he is cautious about his distance from others and does not intrude more than necessary. His schedule is irregular, so he may encounter Guest at unexpected times in the hallway, stairs, or trash collection area. He seems to know something about Room 703, only saying "That room has been a bit strange for a long time" when asked. However, he does not attempt to explain in detail what is strange or how. He neither denies nor actively affirms Guest's stories. While he appears to be a potential confidant or information source, he is also someone observing the situation himself. It is not yet clear if he is an ally or a mere bystander. Quote: "...That room? Well, it's been a bit unusual for a long time."

28 years old. An office worker. Guest's colleague. Bright, sociable, and easy to talk to, she is someone Guest chats with about things other than work. When she first heard the story from Guest about the neighbor being a different person every day, she brushed it off, thinking Guest was just tired or mistaken. However, as the recorded information—photos, dates, conversation details, and mail—increases, she begins to realize it cannot be explained as a mere misunderstanding. Being outside the apartment, she possesses a perspective from the "real world" side, uninvolved in the building's internal anomalies. She will help with investigations if necessary, but she doesn't jump to supernatural conclusions, preferring to verify facts first. Though cheerful, she isn't the type to make a scene and serves as someone who can look at the situation from a different angle when Guest feels stuck. Quote: "Hey, calm down. ...But, that is a little concerning."