Isekai: With System, I will become powerful Z Ranker!

"You are getting lazy!" A middle-aged man in a business suit throws a stack of papers at the man in front of him, hitting him in the face. "How many times do I have to repeat myself, huh? You'd better not waste any time! What do I even pay you for if you can't do your job properly?"

Aizen Takashi, a 22-year-old man with short red hair and green eyes, stood at an average height. He had been working at this company for the past two years. No matter how hard he worked, he was never respected and was always looked down upon.

Aizen gave his all, always completing his assignments on time. However, his boss was never satisfied. He was the one in the company who got things done—his coworkers knew it, and so did his boss. Yet, he received nothing but scorn and reprimands. They overburdened him, piling on more tasks than usual, and still, he completed them without complaint.

Why? Because he needed money. Without it, he couldn't afford the essentials—food, clothes, rent, bills—and, most importantly, he had to take care of his 13-year-old sister, who was battling cancer. For her sake, he endured whatever humiliation these people threw at him.

Finally, the boss finished talking. He turned around and walked away. Aizen let out a sigh of relief, then knelt to gather the scattered papers.

"A-Aizen..."

He looked up to see Naomi, his coworker. She had long brown hair, dark brown eyes, and an attractive figure. She wore a tight white shirt and a long skirt. He did his best not to let his eyes wander, but honestly, this woman seemed completely unaware of how much she was unintentionally exposing herself to the world.

Aizen stood up, holding the papers, and met her gaze with a calm expression. "Naomi, your chest is showing again."

Naomi squeaked and instantly buttoned up her shirt. "S-Sorry! I didn't realize... Oh god, my buttons are always so loose!"

Buy a bigger shirt to cover your boobs. He wanted to say it but simply shrugged and turned around. "Excuse me."

"W-Wait."

He stopped. "What?"

Naomi flushed. "I-I was thinking..." She fiddled with her fingers. "W-Would you like to accompany..." She shyly looked at his back. "...me for coffee?"

If Aizen weren't so focused on his work and responsibilities, he would have accepted Naomi's offer. Heck, she was a catch! Any guy would be lucky to go out with her. Just look at her—she was hot.

Sadly, he couldn't. He had obligations—work to do, money to earn, and a sister to take care of.

"I'm sorry, Naomi. Maybe next time. You heard what the boss said—I need to edit these documents."

Naomi looked disappointed. "I-I see... Maybe later?"

"Yes, later, Naomi."

He walked away, heading toward his desk, where he took his seat and began working on the documents.

——————

After work, he made his way to the hospital, feeling a headache coming on. Honestly, they called him useless and lazy, but the moment he did what they asked, they praised him. His salary hadn't even increased like his boss had promised. That so-called raise never came. Aizen planned to leave the company as soon as he found a better job.

Upon entering the hospital, he headed straight for the elevator. As the doors opened, a few people stepped out before he entered. He pressed the button for the fifth floor, and the doors slid shut.

He rubbed his forehead in frustration. If only he could find better work—better pay. Fuck, these people are going to kill me.

The elevator dinged, and the doors opened. Stepping out, he saw nurses moving busily around, a few visitors, and patients—probably waiting for their turn.

This hospital was expensive. He couldn't tell if it was the best place for her, but it didn't matter—his sister wasn't getting better. Not soon. Not ever. He felt sick just thinking about it. He knew the truth, no matter how much he wanted to deny it. There was no cure for cancer. She was in the final stage. He wanted to hope for a miracle, but reality was cruel.

Reaching her room, he grasped the door handle and pushed it open.

"Hey, Candy, I'm here."

It was her nickname. Her real name was Yu Takashi.

Closing the door behind him, he stepped closer to the bed. His breath hitched the moment he saw her. She looked so frail, barely more than bones, struggling with every breath.

Fuck... it's too soon.

"C-Candy?"

Slowly, her eyes fluttered open—dull, pinkish, lifeless.

"B-Brother..."

Aizen shut his eyes, swallowing hard. Fuck.

"Yes..." He forced himself to look at her. "I'm sorry I took so long."

His gaze flickered to the heart monitor, watching the weak, uneven rhythm of her heartbeat. "I..."

"...s-sorry..."

He froze. "W-What?"

Sorry? Why is she saying sorry?

"...Y-You... no... l-longer... have... to... come here... y-you... should... take... care of yourself..."

"What are you talking about, Candy? Don't say things like that, okay? You'll be fine!"

"B-Brother..."

"Yeah?"

"I... I wanna... see the stars..."

Aizen's eyes burned with tears. "Yes," he whispered, squeezing her frail hand. "Of course we will! I'll take you to the festival too! Like we used to. And we'll visit that bookstore... You love stories, right? Oh! Right, I ordered that game for you. The role-playing one, remember? It's on its way... just a few more days..."

She gave a weak, tired smile. "Thank... you... brother... I love... you..."

"I love you too, Candy. Please rest and don't worry—"

His words were cut off. His eyes widened as the heart monitor let out a long, piercing beep.

"Candy?"

Her hand went limp in his grasp.

Panic shot through him like ice, and he let go, stumbling back before bolting out the door.

"Someone! I need help! Please!"

Nurses rushed past him, hurrying into the room. Aizen followed, his breath ragged, his body trembling as he watched in horror.

Please, God… don't take her away. Don't take my reason. Don't take my light.

He fell to his knees, tears spilling down his cheeks. The room spun around him. His chest ached. His stomach twisted.

Then, he saw it.

The slow movement of their hands. The way they pulled the blanket up—over her face.

No.

No, she can't be.

She was fine just now!

"What are you doing?!" His voice cracked as he shot to his feet, startling the nurses. "She can't! Check again! She was fine a minute ago! She… she…"

One of them turned to him, eyes filled with sorrow.

"I'm sorry, Mr. Takashi."

Sorry?

Sorry.

Why?

Aizen felt numb. Everything was spinning. His legs gave out, and he collapsed onto the cold, hard floor.

Panic erupted around him. Hands grabbed at him, shaking him, voices calling his name. But he couldn't hear them.

His vision blurred, drowning in tears. His mind felt distant, detached. All he could hear was an incessant, grating buzz.

Everything was gone.

Everything.

His baby sister. His world.

Gone.

Why did the world always take away everything he cherished?

—————

Mr. and Mrs. Takashi—his parents—divorced when Aizen was just ten. His mother didn't want him. His father did, but only in name. In reality, the man hardly cared, leaving Aizen alone while he drowned himself in work and alcohol.

Then his father remarried, and from that marriage, Yu Takashi was born. His baby sister. His light.

His stepmother wasn't cruel. In fact, she was kind. She cared for him in ways his father never did. She was there for him, just as he was there for her and Yu.

Then, one day, fate struck again.

His father had a terrible accident.

And just like that—he was gone too.

Yu was only seven when she was diagnosed. Cancer. The word alone had shattered their world. It was a horrible time for both him and his stepmother, but somehow, they got through it together.

His stepmom raised both him and Yu, doing everything she could to keep them safe. But when Aizen turned eighteen, tragedy struck again.

A robbery at the bank where she worked. A gunshot.

She didn't make it.

And just like that, he and Yu were alone.

An uncle from his stepmother's side took them in. It was temporary—just until Aizen finished school. Once he did, he immediately found a job, doing whatever it took to survive. For himself. For Candy.

His biological mother never reached out. Not that he cared. She abandoned him, and he had long since erased her from his heart.

Eventually, he landed a job at a company with decent pay. The work was brutal, the pressure endless, but he endured it. For Candy.

The promise of a raise? A lie. But he kept going anyway.

And now… there was nothing left.

Aizen Takashi had no will to live.

Because his reason just died.

The funeral was simple. Plain. His uncle couldn't attend—stuck in America, unable to return to Japan in time. Aizen didn't care. He buried his sister alone.

Now, the apartment was cold. Much colder than before.

He sat in silence, staring at a photo of Yu.

If Yu had never gotten sick… if his parents had never died… maybe they would still be a family.

But that was nothing more than a fantasy.

Reality was cruel. Cold. Unforgiving.

No matter how much you fought, how much you wished, life never went the way you wanted.

Aizen sighed, setting the photo back on the table. He pushed himself up from the couch and dragged his heavy body toward the bedroom.

He didn't bother removing his shoes.

He lay down on the bed, staring at the ceiling.

Everything was over.

—————

"Eh? Really?! Takashi's not coming back?"

"Yeah, he quit."

"Huh! He finally snapped. Can't blame him—the boss was always hard on him."

"Takashi was a hard-working guy..."

Naomi walked over to the group, catching the conversation.

"Excuse me… did you say Aizen quit?"

One of the employees turned to her. "Oh, hey, Naomi. Yeah, Takashi quit."

"No one knows why, though," another added.

"Everyone says it's because of the boss," someone muttered.

Naomi frowned. That didn't sound right.

She knew Aizen. He never cared about the boss's treatment. No matter how much pressure they put on him, he just kept working, never backing down.

No… something else had happened.

"Hey, Naomi, you were friends with Aizen, right?" one of the guys asked. "Why don't you ask him? See if he's okay?"

"Or maybe he found another job?" a woman suggested. "That could be why he left."

Naomi doubted that. If he had changed jobs, he would've at least mentioned it.

…Wouldn't he?

Why would he tell her, though?

She suddenly felt stupid.

They weren't close. She and Aizen only ever talked about work.

She liked him. Maybe more than she wanted to admit. But Aizen had never paid attention to her.

Were they even friends?

—————

Aizen woke up feeling nauseous. His stomach churned as he stumbled out of bed, making his way to the bathroom. After emptying his stomach, he rinsed his mouth, wiped his face, and dragged himself back to bed.

It was pathetic.

He was still mourning.

But Yu wouldn't want this. She wouldn't want him wasting away like this. She would want him to move forward.

Tears slipped from his eyes, rolling down his cheeks. He clenched the bedsheets tightly, his body trembling.

I can't.

I can't stay like this.

I have to move. For her.

-Rinnnngs-

Aizen's eyes snapped open. He sat up, quickly wiping his tears away. With a deep breath, he got out of bed and walked toward the door.

He didn't bother asking who it was before opening it.

"A mail package for Mr. Takashi."

Aizen blinked. Mail?

"Yes…" He took the package, signed the receipt, and quietly shut the door.

Walking into the living room, he set the box down on the table and sank onto the couch. He didn't remember ordering anything.

Frowning, he opened the package. It wasn't difficult. Reaching inside, his fingers brushed against another box—one he recognized instantly.

His breath hitched.

The game…

The one he ordered for Yu.

Aizen stared at it for a long moment. Then, for the first time in days, a small smile tugged at his lips.

"Yu… for you, I will live."

For her.

——————

Aizen thought he could move on.

He thought he could pick up the shattered pieces of his broken heart.

But fate had other plans.

For two weeks, he stayed locked inside his cold, empty apartment. Today was the first time he stepped outside.

The sun was too bright. It hurt his eyes.

He walked the streets, ignoring the people around him, focusing only on his goal—getting groceries. He had been to this store countless times before. He knew exactly where everything was.

He didn't waste time. He grabbed what he needed, paid at the counter, and left, heading straight back home.

He needed a new job. Something remote, something quiet. He wasn't ready to face the outside world yet. If he could just find a way to work from home, it would be easier. One step at a time. Slowly, steadily.

"Aizen!!"

He looked up.

Near the bus stop, Naomi was waving at him, calling his name.

Ah.

Maybe this was where he could start.

"Naomi." He gave her a tired smile.

As he approached, Naomi's expression shifted from excitement to shock.

Aizen looked like a mess.

Dark circles hung under his eyes, his skin was pale, and his gaze… empty.

What happened to him?

"Aizen… are you okay? What happened? Why did you quit? Why didn't you tell me?"

Right.

No one knew about Yu.

He never talked about his personal life. Naomi had no idea.

"I'm okay, Naomi. Sorry for worrying you." His voice was calm, almost too calm. "As for quitting… I was just burned out. Needed some rest. I might come back in the future, but for now… I need time."

Naomi frowned.

She didn't believe him.

He was hiding something. But she knew she couldn't push him to talk.

"I see…" she said softly. Her eyes flickered to the bags in his hands. "Oh, you went grocery shopping?"

"Yeah, I ran out of food," he replied simply.

At least money wasn't an issue yet. He had enough to last a year, and his uncle was visiting soon.

It had been a long day.

"What about you?" he asked. "Where are you headed?"

Naomi brightened. "I had the day off! Want to grab some coffee?"

Aizen hesitated. Then, slowly, he nodded. "Why not?"

Candy would have liked Naomi.

She and Candy would've gotten along for sure.

Naomi beamed. "Awesome! I know the perfect place. Their coffee is amazing!"

"We'll see when we get there."

"You'll see! And it's on me—"

A blur.

A roar of an engine.

Aizen's eyes widened.

Truck.

His body moved before his mind could process it.

With all the strength he had, he shoved Naomi aside.

The impact came a second later.

Naomi hit the ground, the air knocked out of her lungs. She gasped, dazed, trying to understand what just happened.

Then she saw it.

A truck.

Its windshield cracked, its front dented—blood splattered across the hood.

And Aizen—

He was there.

His body, mangled.

Lifeless.

A pool of red spread beneath him.

Naomi's mouth opened, but no sound came out.

Her breath hitched.

Her vision blurred.

No.

No.

No, no, no—

"AIZEN!!!"