After Reaching the Happy Ending, I Was Locked up by the Extremely Possessive Heroines I Had Conquered - Chapter 3.2: From My Stepsister’s Conquest to Her Yandere Transformation

Chapter 3.2: From My Stepsister’s Conquest to Her Yandere Transformation

“Really, really?” she pressed.

“Really.”

“If you’re lying, you’ll swallow a thousand needles.”

“Go ahead and bury me in the dirt if I do.”

“I’m not that kind of person.”

“Haha, I know. You’re a kind little sister, Mahiru.”

“Ugh, you’re so annoying.”

She didn’t meet my eyes at the end, but from that day, her attitude started to change.

She became less cold, responding to me more often. We laughed together over curry in the living room and talked about nothing under the stars at night. Her smiles grew, and light began to return to her indigo eyes.

“Akira, I put a ton of chocolate in the curry as a secret ingredient today. What do you think?” she asked, initiating a conversation for once. She still called me Akira, but there was warmth in her voice.

“It’s delicious! A bit sweet, but delicious!” I exaggerated my praise and patted her head. She smiled shyly and puffed out her breasts, then she said, “This is nothing.”

And so, we grew closer as true siblings.

But the islanders’ discrimination didn’t vanish so easily.

As if following the original story’s script, hardships kept piling on Mahiru.

*

One day, I saw Mahiru surrounded by girls in the school hallway. They mocked her heritage and whispered cruelly.

“Outsider blood is so dirty, right?”

“Ugh, stay away. I don’t want your filthy blood rubbing off on me.”

Mahiru looked down silently, her eyes fixed on the floor. I stepped in immediately, glaring at the girls.

“Hey, cut it out. What did Mahiru ever do to you?”

The girls dispersed awkwardly, but I caught their parting shots—things like “playing siblings” and “gross, even though they’re not related.”

I didn’t care. I’d expected as much.

That night, in the living room, Mahiru muttered softly.

“Akira, please stop protecting me. If this keeps up, you’ll get harassed too.”

“I don’t care about that. You’re my sister. No matter what harassment comes, I’ll always protect you.”

“But…”

“I’m doing this because I want to. You don’t need to worry.”

I reassured her repeatedly, but she just looked down and said nothing.

And then came the turning point from the original story—the event where Mahiru, broken by tears, takes her life on the cliff.

It stemmed from incidents at school. A few days after finding my shoes filled with thumbtacks and my textbooks thrown away, it happened.

Under the moonlight illuminating the sea, Mahiru stood quietly on the cliff.

“Mahiru!”

She was at the cliff’s edge, her eyes fixed on the sea. Her black hair swayed wildly in the night breeze, her shoulders trembled faintly, and tear tracks stained her cheeks.

“Akira, I can’t take it anymore. I can’t stand that I’m causing trouble for you,” she said weakly, her voice barely audible, as if fading away. It was exactly like the bad ending in the original story. Before I knew it, I was running toward her.

“Mahiru!”

“Because of this filthy blood!”

As I reached out, Mahiru pressed a shard of glass from the ground against her throat.

Blood slowly trickled out. I snatched the glass away and pulled her into a tight embrace.

“Idiot! What are you doing? If you were gone, I’d be the one in trouble! I’d be just as alone!”

“Akira…” Her body was cold and trembling. Blood from her throat dripped onto the rocky ground.

My hand, cut from grabbing the glass, was bleeding too.

We faced each other, both bleeding. I spoke slowly.

“I’m your big brother. I’m not going anywhere. I’ll always be by your side.”

“Even though we’re not related by blood?” Her voice broke with tears.

“We are connected. Look, we’re both bleeding right now. Our blood is flowing together, into the sea.”

I wiped her tears and looked into her indigo eyes.

“We’re blood-related siblings now. So, will you call me it? Call me big brother.”

“What’s that supposed to mean?” she mumbled.

“I told you, I’m a siscon.”

“You’re such an idiot, Akira.”

“It’s big brother.”

“You’re an idiot, big brother!”

Her voice trembled, but it carried a hint of joy. Then she called out again.

“Big brother!”

“Will you… stay with me forever?”

Her tearful eyes shone with a light I’d never seen before in this world—Mahiru Akiyoshi’s true radiance.

Determined never to let that light fade, I grinned and said, “Yeah, I promise.”

“Really?”

“Really.”

“Really, really?”

“Really. I’d swear on this blood.”

It was a heavy oath, but for Mahiru, tormented by blood, it felt like the most trustworthy promise.

“Big brother! Big brother! Big brother!” she cried, burying her face in my chest, sobbing as she called out to me.

And so, we avoided the original story’s bad ending.

The islanders’ discrimination didn’t completely disappear, but with me, her brother, by her side, Mahiru no longer felt alone.

The story reached its happy ending. And they lived happily ever after.

Or so it should have been.

“Big brother is mine forever.”

“Why do we sleep in separate beds? Siblings should sleep together, right?”

“Mother’s coming back next week. I can’t forgive her for invading our sibling love nest, so I put a chain on the door.”

“My only family is big brother.”

Mahiru had become a slightly possessive sister. Looking back, ignoring this subtle shift might have been a mistake.

But come on, what could I do? I was thrilled to finally get close to Mahiru. Getting a bit carried away was only natural.

And so, Mahiru Akiyoshi was conquered—and turned yandere.