Every evening at 19:20, the apartment stopped having boundaries. The first time, I leaned against the bedroom partition... and passed halfway through it. I pulled back and pressed my hand against the paint. Resistance... then nothing. My fingers were on the other side. Floors remained solid. Ceilings too. Stairs worked normally. Everything vertical had become optional. At 06:00, the walls became solid again. The next evening at 19:20... it happened again. After a week, fear became routine. I walked through the side of a closed supermarket. Through shelves. Through locked storage. I took food, clothes, batteries. Then things I didn't need. Nobody stopped me. Then I noticed the cashier hadn't reacted. I stood directly in front of her. "Can you hear me?" Nothing. I struck the counter. I felt it. She didn't. The next morning, after 06:00, a stranger nearly collided with me and apologized. He could see me. That was the second rule. At night... I wasn't hidden. I was excluded. For a while, I liked it. Locks meant nothing. Shop shutters meant nothing. I could enter almost anywhere. But people passed through me as easily as the walls. I could shout beside someone's face and get no reaction. I could go anywhere... but there was nowhere I could be with anyone. Once, I entered a crowded cinema. Every seat was occupied. So I sat where someone was already sitting. For the entire film... two bodies occupied the same place. Only one of us existed to everyone else. Eventually, I stopped watching the time. I slept during daylight. Stopped setting alarms. One evening, I entered the service areas beneath a shopping complex. Past the loading area. Past electrical cabinets. Through a concrete barrier. I found a sealed service cavity inside the building. No entrance. No outside view. Just enough space between structural supports to keep walking. My phone showed nine percent. Then four. Then it switched off. There were no announcements. Nothing changed enough to tell me morning was approaching. I had become used to architecture being harmless. I forgot the rule had an ending. My left arm stopped inside the concrete. One moment it passed through. The next... the structure became solid around it. I pulled back. Couldn't. My shoulder pressed against the wall while my arm remained somewhere beyond it. I screamed. Later, machinery started somewhere overhead. Footsteps crossed above me. Morning workers. Nobody came. Then I understood. This wasn't a place people entered. It was space left inside the building for pipes, cables and supports. Enough space to stand. Enough air to survive. Nothing to do except wait. Hours later... the concrete released my arm. 19:20. I walked through the structure and outside. I thought I was free. The next morning... nothing changed. People continued passing through me. I found a public clock. 08:47. Then 10:16. Then afternoon. I went home. The building manager was packing my belongings into numbered plastic crates. I stood beside him. Said my name. Then shouted it. He never looked up. On the counter was a printed notice. TENANCY TERMINATED. Reason: Occupant missing. I thought the walls changed every evening. They didn't. The world always recognized them. For a few hours each night... it stopped recognizing me. And somewhere beneath that shopping complex... 06:00 arrived exactly when it was supposed to. Everything returned to normal. Except me.