The cold of the wooden hallway outside the lab seeped slowly through my back, pressed against the wall. My tears had stopped before I knew it. Not so much from crying myself out — they had simply run dry. The backs of my eyes stung with a raw, burning ache. When I rubbed my swollen eyelids, the unreliable light of the old fluorescent lamp blurred and bled into my vision. "[gentle]...Shouldn't you go home?" A quiet voice drifted down from beside me. Kurisu was sitting with her knees drawn up, leaning against the wall just like I was. Her long, reddish-brown hair, reaching all the way to her waist, seemed to float faintly in the dim hallway. Her face, too, was utterly exhausted. The dark circles carved beneath her eyes cast deep shadows in the corridor's light. "[whispers]...I can't go home." I answered in a hoarse voice, staring down at my own fingers clasped together on my knees. "Um, well... I can't leave Okabe-san... alone." If I went home now... I had a feeling that, most likely, I would never be able to come back here again. I knew it in my bones — that I could never be Okabe-san's number one. And yet, just standing here, flustered and helpless, I felt miserable, pathetic. Even so. *(I don't want to leave him.)* Contradictory emotions swirled in a vortex deep within my chest. For a long moment, Kurisu simply gazed at me without a word. Her violet eyes were serious, as if trying to ascertain something. Then, finally, the corners of her mouth relaxed just a little. "[gentle]...I see." With that, she placed a hand against the wall and stood up. "[gentle]Then, can you take over for me? I'm going to take a short nap. Now that you're here, I feel like I can finally rest easy." At those words, I looked up with a start. "[surprised]M-Me...? Are you sure it's okay?" "[gentle]It's fine. If anything happens, wake me up right away." Saying only that, Kurisu disappeared into the small room next to the lab. For a while, I remained sitting there, unable to move. *(Is it really okay for it to be me?)* I was anxious. But, more than that, just a little bit, I was happy. That I might be able to help. Just thinking that, even in the middle of the night, lit a small lamp inside my heart. --- Early Friday morning. The summer sunlight was still gentle, and the light streaming through the window faintly illuminated the dusty air of the lab. Okabe-san was still asleep. No — "unconscious" was probably a more accurate word than "asleep." His face, lying on the sofa, was shockingly pale. Every now and then, his brow furrowed in pain, and a hoarse breath escaped his dry lips. I was cooling a towel in the water of the basin I'd placed beside me. *(His fever won't go down.)* Just holding my hand over his forehead, I could feel the heat radiating from him. For three days and three nights, he'd barely slept, barely eaten or drunk anything, fighting against something as immense as time leaps and world lines. It was only natural. He had watched Mayuri-san die. Over and over. That fact echoed inside my head. *(What must he have felt, making those time leaps?)* I gently placed the now-cool towel on his forehead. The deep wrinkles between Okabe-san's eyebrows seemed to ease, just a little. He was kind, and strong, and always looked out for me — the person who even made me a lab member. That person was now, right before my eyes, on the verge of breaking, like a small child. A cold shiver ran down my spine. The door creaked open. I turned to see Kurisu standing there. She must have slept a little; her complexion looked somewhat better than it had last night. She walked over silently and sat down on the floor beside me, just as I had. "[serious]...Has he been talking in his sleep?" "[whispers]No... he seems a little calmer now." I shook my head slightly. "[serious]I see." Kurisu gazed intently at Okabe-san's sleeping face. Her profile was still utterly exhausted, yet surprisingly composed. I gathered my courage and voiced the question I hadn't been able to ask yesterday. "[whispers]Makise-san... what is a D-Mail?" Kurisu's shoulders twitched slightly. "[serious]...So you know about it." "[whispers]Okabe-san was talking in his sleep... about world lines, and things like that." A long silence filled the room. Only the second hand of the wall clock mechanically ticked away the seconds — *tick, tick*. "[serious]...Fine. I'll tell you." As if steeling herself, she began to speak, quietly. "[serious]A D-Mail is a technique for sending mail to the past. Okabe discovered it by accident." Mail... to the past. "[serious]When you send that mail, the past changes. And then, the world line — the branching structure of causality — shifts, and you move to a world completely different from the current one." The world... changes. "[serious]And in this world line... it has been determined that Shiina Mayuri will die." Mayuri-san... ...will die. My mind went completely blank. "[serious]To avert that death, Okabe has been repeating time leaps, over and over. Sending only his memories to the past, again and again, witnessing the moment of her death each time." Over and over. Witnessing his best friend's death. "[crying]Okabe-san... was he... all alone, this whole time...?" My voice trembles. The scene before me blurred and warped. That person, kinder than anyone else. The person who called someone like me a comrade, who protected me. All alone, facing his best friend's death again and again, and still, without giving up, fighting. Wearing his heart down until it was in tatters. I... didn't know anything. I didn't even try to know. I just let Okabe-san protect me, indulged in his kindness. I was caught up in my own feelings, swinging between joy and despair over whether my love would reach him. Tears welled up and wouldn't stop. I couldn't make a sound. My throat tightened, and I couldn't breathe properly. Kurisu said nothing. She just silently placed her handkerchief on my lap. "[crying]I'm sorry... someone like me... I..." I can't find the words. I just covered my face with both hands and cried, stifling my sobs. I hadn't known even the smallest fragment of his suffering. That, more than anything, was painful, was mortifying. How long did I stay like that? "[serious]...There's one more thing I should tell you." Kurisu looked straight at my face, now a mess from crying. "[serious]There isn't just one world line where Mayuri's death is determined. He has experienced her death across multiple world lines—" That was when it happened. "[crying]...Kurisu... restock the... Dr Pepper..." At that sudden, absurdly timed voice, both Kurisu and I froze completely. The two of us stared at Okabe-san, lying on the sofa. His face was still twisted in pain as he continued to murmur in his sleep. Deep wrinkles furrowed his brow. Large beads of sweat dotted his forehead. His breathing was ragged. But those words just now... "[cold]...Really? *Now*?" Kurisu muttered in a deflated voice. Without thinking, I let out a soft breath. I laughed. "Fufu..." At a time like this, this person... When we were talking about such impossibly heavy things — world lines, death... ...he asks for a Dr Pepper restock. "[sad]...He's such an idiot." Kurisu sighed, but the corners of her mouth relaxed slightly into a wry smile. For just a fleeting moment, the oppressive atmosphere in the room lifted, ever so softly. But. "[crying]...Mayuri... wait for me... I'll... definitely..." Immediately after, at the words wrenched from his lips, my smile vanished. Calling that name again. Over and over. That voice was so pained, so full of longing. *(Okabe-san's heart... is completely filled with Mayuri-san, after all.)* It was something I already knew perfectly well, but a sharp pang shot through my chest. I placed my hand beside Okabe-san. I wanted to grasp it. I wanted to take his hand and tell him it would be alright. But I can't. *(It's not a hand I'm allowed to hold.)* I pulled back the fingers I had started to reach out. Instead, I picked up a fresh towel. I wrung it out in cold water again and gently placed it on his burning forehead. This was all I could do for him right now. --- Early afternoon. When the strong sunlight was bleaching the window white, the anomaly came suddenly. *Tap, tap*, came a light knock. "[excited]Okarin, listen! I came to visit!" Along with a bouncing voice, the lab door swung open with force. My heart leaped. Standing there was a petite girl. Her soft, semi-long hair, a deep navy blue, reached just past her shoulders. A small scrunchie swayed at the side. Her large, round, clear blue eyes darted around, looking over the room. Shiina Mayuri-san. Seeing her properly for the first time. The person from that photo, back then. Okabe-san's childhood friend. The person whose death is determined across multiple world lines. "[excited]Ah! Okarin really is asleep! You dummy, you're pushing yourself way too hard!" Laughing merrily, Mayuri-san hurried over to the sofa where Okabe-san lay. Then, she began straightening his disheveled blanket. Her movements were practiced, so natural, as if she had been doing this forever. She is going to die. This smile will disappear. Even though my head understood that, her smile was so astonishingly bright, so warm. "[excited]Oh! Are you one of the lab members? Nice to meet you, I'm Mayuri! It's so nice to meet you!" When Mayuri-san noticed me, her expression lit up and she waved. There was no cloudiness in that smile. No malice, no lies, no shadow. It was as if it were made of nothing but pure light. And that was precisely why my chest ached as if it were being gouged out. "[whispers]...N-Nice to meet you. I'm Urushibara Ruka." My voice trembles. I can't manage a proper smile. "[excited]Can I call you Ruka-chan? Okarin was bragging about how a super cute girl became a lab member!" Okabe-san... was talking about me. My heart throbbed. But more than that, a sharp pain ran through me. Why, of all people, do *you* have to say something like that? "[gentle]Okarin, you know... he's actually kinder than anyone. He tries to carry everything for everyone all by himself... so watching him, it makes me really worried." Mayuri-san said this while gently combing her fingers through sleeping Okabe-san's bangs. "[gentle]So, having someone like you, Ruka-chan, by his side... that makes me really happy." Those words. Those eyes. *(Ah... this person truly doesn't know anything.)* Neither the fate of her own death. Nor how much Okabe-san is breaking his heart for her sake. "[whispers]...Is it really okay... for it to just be someone like me?" Before I knew it, I had said that, looking down. Mayuri-san looked at me with a puzzled expression, then smiled softly. "[excited]It's totally okay! Because all the lab members are comrades!" Comrades. There wasn't a single shred of malice in that word. And that, more than anything, pierced my heart. --- Evening. Kurisu excused herself, saying she was "going to buy some medicine," leaving just me, Mayuri-san, and the still-sleeping Okabe-san in the lab. The sound of cicadas droned noisily in the distance. "[gentle]Hey, Ruka-chan." Mayuri-san peered into my face with a mischievous look in her eyes. "[gentle]Ruka-chan... do you like Okarin?" I thought my heart had stopped. "[surprised]Huh... um, well..." The words caught in my throat. I could feel my face growing hot. "[laughing]You don't have to hide it. It's written all over your face." Mayuri-san giggled. There was no sense of superiority in that smile, no pity. There was only the pure kindness of someone genuinely concerned about me. That was exactly why. Exactly why I felt I had to say it. "[sad]...To Okabe-san... Mayuri-san is the most important person, isn't she?" My own voice sounded terribly distant. Mayuri-san tilted her head,