DAY 3 DIMENSION: 3 And beneath it, a line that had never appeared before was added. “ORIGINAL: 2” I read those words over and over again. “Original... 2?” I had no idea what it meant. But I had no time to think about it. My vision suddenly turned white. The next moment, I was lying in bed. There was a ceiling. Walls. A window. There was left and right, up and down. I shot upright. “I’m back...?” I looked at my hands. Normal hands. I touched my stomach. Nothing felt strange. Unlike in yesterday’s two-dimensional world, the inside of my body was hidden again. I rushed to the window. Outside was the city I knew. Cars moved along the streets. Laundry swayed from the balconies of the apartment building across from mine. Clouds floated in the sky. There was depth. A completely three-dimensional world. “I made it back.” The words escaped my lips. It had only been two days. And yet, it felt as though I had spent weeks wandering through other worlds. I checked my phone. 7:12 a.m. The date was two days after the morning this all began. Time itself seemed to have passed normally. I checked my notifications. There were no mysterious messages. I let out a long breath. It was over. Or so I thought. Then the front door opened. “You’re awake?” A woman’s voice. I froze. Who was that? Footsteps approached. The bedroom door opened. A woman I had never seen before peeked inside. “You’re up early today.” I couldn’t say anything. She looked at me, confused. “What’s wrong?” “...Who are you?” Her expression froze. A few seconds later, she laughed. “What kind of joke is that?” I couldn’t laugh. I really didn’t know her. I had no memory of ever meeting her. “No, seriously...” The smile disappeared from her face. “Are you still half asleep?” She pointed to a framed photograph beside the bed. It showed the two of us together. Standing by the sea, our shoulders pressed together. I picked up the frame. That was definitely me. But I had no memory of taking this picture. “When was this...?” “On our trip last year.” Last year? I hadn’t gone on any trip last year. She looked more worried by the second. “Are you okay?” Without answering, I opened my phone. I checked my photos. There were hundreds I had never seen before. Me having dinner with her. Me at an amusement park with her. Me celebrating her birthday. Then my finger stopped on one photo. The two of us were smiling and showing off rings. The date beneath it was from one year ago. “Am I... married?” The woman went completely silent. I nearly dropped my phone. This wasn’t my original world. This was a three-dimensional world where I had lived a life I knew nothing about. At that moment, the words of the man from yesterday returned to me. “Who is the other person inside you?” Was this what he had meant? Was there another “me” inside me who had lived an entirely different life? My phone vibrated. It was that notification again. A short message appeared on the screen. “DIMENSION: 3 SYNCHRONIZATION STARTING” “Synchronization...?” The next instant, a violent pain shot through my head. Memories I had never experienced flooded into me. The day I first met her. The night I confessed my feelings. Our wedding. The day we moved into this apartment. None of them were my memories. And yet, they felt like my own. I dropped to my knees. “Stop...” The woman rushed toward me. Suddenly, her name appeared in my mind. Misaki. I shouldn’t have known it. But I did. I even remembered loving her. Fear gripped me. If the synchronization continued, what would happen to the original me? New text appeared on my phone. “SYNCHRONIZATION: 12%” The number rose. 18%. 27%. 35%. With trembling hands, I threw the phone onto the floor. But the screen didn’t turn off. 42%. “Stop!” 50%. At that moment, the number froze. Then another message appeared. “MISMATCH DETECTED” Below it were the words I had seen before. “ORIGINAL: 2” Then a new question appeared. “WHICH LIFE DO YOU BELIEVE IS REAL?” Two choices appeared beneath it. “A: THE LIFE YOU REMEMBER” “B: THE LIFE THAT EXISTS IN THIS WORLD” Without hesitation, I reached to press A. Then Misaki spoke. “Hey.” I turned around. She was crying. “You’ve been acting strange since yesterday.” My finger stopped. “Yesterday?” Yesterday, I had been in a two-dimensional world. I shouldn’t have been in this world at all. “What was I doing yesterday?” Wiping away her tears, Misaki answered. “You were here. Just like always.” A chill ran down my spine. Then who had been living my life in this world yesterday? My phone vibrated again. The choices disappeared. In their place, a single line appeared. “ORIGINAL: 2 DOES NOT REFER TO YOU” I stopped breathing. Immediately afterward, the screen went black. DAY 4 DIMENSION: 4 And finally, one last message appeared. “TOMORROW, YOU WILL WATCH THE MOMENT OF YOUR OWN DEATH.”