Aiko Sato sat at her desk on the third floor of the modest office building in the business district, the late afternoon light filtering weakly through the rain-streaked windows. She was in her late thirties, with shoulder-length black hair pinned back neatly and a tired but kind face that showed the faint lines of someone who had worked hard for years to provide for her family. Her blouse was a simple white cotton one, slightly wrinkled from the long day, and her dark skirt was practical for the office. The open-plan workspace buzzed with the low hum of keyboards, the occasional ring of a phone, and the quiet chatter of colleagues wrapping up their tasks. The air smelled of printer ink, stale coffee from the break room, and the faint dampness that always seeped in on rainy days.
Beside her, Yumi Takahashi — the mother Mimo had killed the previous evening — was finishing her last email of the day. Yumi was a warm, chatty woman in her early thirties, with short hair and a bright smile that made the office feel a little lighter. She and Aiko had worked side by side for almost five years, sharing lunches, complaining about deadlines, and swapping stories about their children. Yumi's daughter was six years old, and she often showed Aiko new drawings the girl had made.
"Closing time already," Yumi said with a sigh, stretching her arms above her head. "I promised my little one I'd pick her up from the park today. She loves the slide after it rains — says it feels like a water slide." She laughed softly, the sound genuine and light. "You should come with us sometime, Aiko. Your kids would love it too."
Aiko smiled back, though her own smile was smaller, more tired. "Maybe next week. Today I just want to get home and put my feet up. The rain makes everything feel twice as heavy."
They finished their final tasks in companionable silence. Yumi gathered her bag, slipped on her light jacket, and waved as she headed toward the elevator. "See you tomorrow! Tell your husband I said hi."
Aiko watched her colleague disappear down the corridor, then turned back to her computer to shut it down. The office was emptying quickly, desks going dark one by one. She gathered her own things, locked her drawer, and left the building a few minutes later, umbrella already open against the light drizzle.
As Aiko walked along the wet sidewalk toward the park where her own children sometimes played, she passed the familiar playground area. The colorful kiddie slide glistened with rain. A mother and her young daughter were standing near it — Yumi and her little girl. Aiko smiled to herself, about to call out a greeting, when she saw the third figure.
Mimo stood right there in the open, already in her school uniform, no mask or suit. Her face was completely blank — no anger, no excitement, just calm, emotionless detachment. She bent down, picked up a rusted metal pipe lying discarded near the slide, and swung it without hesitation.
The first blow struck Yumi across the side of the head with a dull, sickening thud. Yumi crumpled instantly to the wet grass, blood trickling from a deep gash on her temple. The little girl screamed in terror. Aiko froze behind a nearby tree, heart hammering, unable to move or scream.
Mimo moved quickly and methodically. She brought the pipe down again on Yumi's back as the woman tried to crawl toward her daughter, the impact producing a horrible crack of bone. Blood sprayed across the damp ground and Yumi's clothes. The mother gasped in pain, hands feebly reaching for her child. Mimo continued swinging the pipe with calm precision — hitting the mother's ribs, arms, and head repeatedly. Each blow landed with wet, cracking sounds, breaking bones and opening new wounds. Dark red blood spread across the grass and the woman's blouse, mixing with the light drizzle into faint pink rivulets.
The little girl cried hysterically, trying to run, but Mimo caught her easily by the arm. She used the pipe to strike the child across the legs, knocking her down onto the muddy grass. Yumi gasped in pain, weakly reaching for her daughter, but Mimo shifted her attention. She stabbed the jagged end of the pipe into the mother's abdomen and chest repeatedly, the metal piercing flesh with sickening, wet sounds. Yumi gurgled, hands trying to push the pipe away as more blood poured out. Her eyes remained wide with shock and desperation as she watched her daughter.
The girl's screams turned to weak whimpers as Mimo stabbed the pipe into the child's small chest and stomach with steady, repeated thrusts. The metal sank into soft flesh, producing horrible squelching noises. Blood welled up immediately, soaking the girl's clothes and the grass beneath her. The child twitched and gasped, tiny hands clutching at the wounds as her life faded quickly. Mimo's face stayed completely blank throughout the entire act — no emotion, no hesitation, no satisfaction — just calm, mechanical efficiency as she delivered the final blows until both bodies lay still, broken and bleeding into the damp earth.
Aiko stood frozen behind the tree, horror choking her throat. She watched Mimo drop the pipe, wipe her hands on the grass, and walk away without looking back. The light drizzle continued, washing faint pink trails into the soil around the two bodies near the kiddie slide.
Aiko turned and ran, legs shaking, heart pounding so hard she thought it might burst. She didn't stop until she reached her own apartment, locked the door, and collapsed on the floor, sobbing silently.
---
Present day, the rain had eased into a light drizzle. Aiko Sato sat alone in her small apartment that evening, the television murmuring in the background with the latest news about the serial killings and the newly announced curfews. She had barely slept since witnessing the horror at the park the previous day, jumping at every creak in the floorboards and every shadow that moved across the window. The image of the blank-faced high-school girl swinging the pipe with cold, emotionless precision replayed endlessly in her mind — the dull thud against Yumi's head, the wet cracks as bones broke, the blood mixing with the drizzle into faint pink trails on the grass.
Aiko clutched a cup of tea that had long gone cold, her hands still trembling. The apartment was modest and tidy: a simple living room with a low table, a worn couch, and family photos on the shelf showing her children smiling on brighter days. The air smelled faintly of rain-soaked laundry drying on the balcony and the leftover dinner she had barely touched. She kept the curtains half-drawn, afraid to let too much of the outside world in.
A soft knock sounded at the door.
Aiko froze, heart hammering. She didn't move. Another knock, firmer this time. She crept to the peephole, peering out with wide, frightened eyes. No one was visible in the dimly lit hallway. The knock came again, patient and steady.
She hesitated, then cracked the door open with the chain still latched. "Who is it?"
No answer.
Before she could close it, a figure moved fast from the side. The door slammed against the chain with sudden force. Aiko stumbled back, screaming, but the chain snapped.
---
Detective Hikaru arrived at Aiko Sato's apartment building less than an hour later. The rain had picked up again, drumming steadily on the roof as he climbed the stairs. He knocked on the door, waiting patiently. No answer. He knocked again, louder. Still nothing.
A sense of unease settled over him. He tried the handle — unlocked. He pushed the door open slowly.
The scene inside was horrific.
Aiko lay sprawled on the floor of her living room, surrounded by a wide pool of dark blood that had soaked into the tatami mats and stained the edges of the low table. Her body was broken in multiple places — deep gashes across her head and temple, shattered ribs visible through torn clothing, and multiple stab wounds to her abdomen and chest. Her eyes were still open, frozen in a final expression of terror and disbelief. Blood had splattered across the walls, the couch, and several family photos on the shelf, turning smiling faces into gruesome smears. A rusted metal pipe lay discarded beside her, its end coated in dried blood.
The apartment was otherwise tidy but now carried the heavy metallic scent of fresh blood mixed with the faint smell of cold tea and rain-soaked laundry from the balcony. The television was still on, the volume low, showing footage of the recent press conference about curfews and the serial killings.
Hikaru stood in the doorway for a long moment, his face grim. He had come to ask Aiko what she knew about Yumi Takahashi — the victim from the park — hoping she might provide a crucial lead. Instead, he had arrived too late.
The killer had gotten to her first.
The rain continued to fall outside, steady and cold, washing the streets clean while the stains inside the apartment refused to disappear.