After Reaching the Happy Ending, I Was Locked up by the Extremely Possessive Heroines I Had Conquered - Chapter 4: From a Scheming Junior to a Yandere

Chapter 4: From a Scheming Junior to a Yandere

After I finished pursuing Mahiru, the next person I met was Toa Watarase.

Her light brown hair curled softly at her shoulders, and she was the hugely popular, scheming junior character in the original story, ‘Black Tide, Great Serpent, Island of Prayers’.

An orphan raised in the island’s foster care facility, she grew up starving for parental love, with an intense need for validation.

She charmed those around her with her mischievous behavior, appearing to get along with everyone, but in truth, she trusted no one.

She only believed in herself. Yet, deep down, she always longed to trust someone.

Toa believed in the island’s superstitions.

“They say there’s a snake god on this island, and if you make a wish on the day the Black Tide meanders, it comes true,” she said.

She wished for parents, but after investigating, she uncovered a secret at the shrine.

The secret was that the three noble families once offered sacrifices to calm the Black Tide’s meandering.

The so-called “endemic disease” spreading across the island was a lie, fabricated to cover up these sacrifices.

When Toa learned this truth, the islanders eliminated her.

But her death’s truth was never revealed, brushed off as the endemic disease—a sickening bad ending.

In the original story, the protagonist chose her, abandoned everything on the island, and fled with her off the island, pursued by the islanders in a desperate escape.

It was the so-called escape ending, but their mutual support and life as a true family felt resilient, bittersweet, and satisfying.

However, choosing that route meant escaping the island, automatically making it impossible to save the other heroines.

So, I decided to take a different approach to prevent Toa from uncovering the island’s secret.

My strategy was to keep her away from the story’s critical point—the Black Tide Shrine.

On top of that, I aimed to fill her loneliness. Specifically, by being incredibly meddlesome.

I met Toa in the school’s backyard.

Right after enrolling, Toa became a school celebrity. Her cute appearance and friendly personality made her especially popular with upperclassmen, to the point of receiving a line of confessions.

Meanwhile, her scheming nature earned her dislike from female students, who whispered behind her back and shot her cold glares.

One day, I overheard a commotion in the backyard. When I reached the source, Toa was surrounded by upperclassmen, her face showing distress.

Apparently, she’d rejected a confession, and they were taking it out on her.

Toa kept a smile, but a closer look revealed fear flickering in her eyes.

“You’re getting cocky! Acting all high and mighty for someone raised in an orphanage!” one of the upperclassmen shouted, reaching for her arm.

She froze, trembling silently.

“Hey, cut it out. She’s clearly uncomfortable,” I said, stepping in and glaring at them.

“…Tch, whatever,” the guy muttered, looking like he wanted to say more but backing off under my stare and leaving.

“Senpai… why did you help me?” Toa asked.

“No real reason. I just happened to be passing by, I guess.”

“That’s not an explanation.”

“I don’t owe you one, do I?”

“…You’re kind of mean, Senpai.”

From then on, Toa started hanging around me.

After school, she’d say, “Senpai, wanna walk home together?” in a sweet voice or sit near me during breaks to chat. She even showed up at my house, arguing with Mahiru over “how to handle me,” which was a whole ordeal.

But back then, I think we had a typical senior-junior relationship. She kept her distance in a way, never talking about anything personal, and I noticed the anxiety hiding behind her smile.

That went on for a while until one day she suddenly said, “Senpai, did you know? There’s a snake god on this island, and if you make a wish on the day the Black Tide meanders, it comes true.”

By the way, the Black Tide meandering is a phenomenon where the Black Tide’s current, flowing from south to north along Japan, curves and twists for an extended period. When it happens, it lasts over a year, affecting the island’s fishing industry with changes in fish hauls and rising sea temperatures.

I didn’t see how the meandering tied to wishes, but it was probably a rumor spread by the three noble families, lacking any real logic.

When I said I didn’t know, Toa asked, “Don’t you have any wishes?” I answered, “Nope,” and she pouted, saying, “You’re such a realist, Senpai. No dreams at all.”

Around that time, Toa’s behavior started getting strange.

She snuck into the library at night or borrowed old island records from a neighbor, poring over them like she was possessed.

Just like in the original story, she seemed to be researching ways to “deliberately cause the Black Tide’s meandering.” To stop her, I got even more meddlesome.

“Wanna eat dinner at our place tonight?” I asked.

Before long, eating dinner with me and Mahiru became a daily routine.

“Come on, eat your veggies,” I teased when she picked at her food.

“You’re like a mom, Senpai. Not that I’d know, since I don’t have parents,” she said with a wry smile, her voice tinged with loneliness.

“Mom’s a bit much, don’t you think? But you can think of this house as home. Right, Mahiru?”

“No way! She’s an outsider. She’s just getting in the way of us siblings!” Mahiru snapped.

“Yet you still cook her portion of dinner,” I pointed out.

“Shut up, you idiot brother!” Mahiru huffed.

“You two really feel like a real family. I’m jealous,” Toa said, looking briefly surprised before flashing her usual scheming smile.

“If you’re ever lonely, come over. Mahiru and I welcome you.”

“I do not welcome her!” Mahiru protested.

“Haha, got it,” Toa laughed.

To Toa, I was just a stranger. I could never replace her family. Still, I hoped to give her a sense of belonging, so I kept being as meddlesome as possible.

*

Despite my efforts, Toa kept digging, getting closer to the three noble families’ secret, heading straight for the original story’s bad ending.

To keep her away from the Black Tide Shrine, I stuck to her even more.

“Toa, isn’t it dangerous to go to the shrine this late? I’ll come with you,” I said one night, spotting her behind the shrine and calling out cheerfully.

“Senpai?! W-Why are you here? …I was just taking a walk!” she stammered, forcing a smile, but her eyes betrayed her panic.

“If it’s a walk, I’ll join you. Come on, it’s safer together, right?”

I grabbed her hand and pulled her away from the shrine. She resisted for a moment but soon reverted to her usual scheming smile.

Then came the story’s turning point—the event where Toa sneaks into the Black Tide Shrine and learns the secret.

Her heart, starved for love, triggers the unraveling of the three noble families’ history of sacrifices.

That night, after sunset, Toa stood alone in front of the shrine’s torii gate.

“Toa!” I called out instinctively.

She turned slowly.

“Don’t go any further—it’s dangerous! Come on, let’s head home.”

“No! I have something I need to do!” Her voice was desperate, unlike her usual self.

“There’s nothing you’re looking for up there!”

I stepped closer, reaching for her arm.

“How would you know, Senpai? Don’t just say whatever!” she snapped, slapping my hand away and shouting, “Stop it!”

But I wasn’t fazed. I stepped forward again and took her hand.

“What are you, Senpai?! Following me at school, outside of school, inviting me to your house even when I say no, feeding me like family, staying by my side when I’m lonely. You won’t let me be alone, even when I want to be. And then you tease me and mess with my head. What are you? Seriously, Senpai…”

Her voice broke with tears, her shoulders trembling as she collapsed.

I silently hugged her shaking shoulders. Unable to hold back, she sobbed loudly.

“Senpai! Senpai!” she cried.

I gently patted her back, like soothing a child, slowly, slowly.

After a while, she calmed down, wiping her tears and sniffling. I handed her a handkerchief, and she blew her nose loudly before murmuring her true feelings.

“I… I’ve always wanted parents. No one loves me. They always leave me.”

“…”

“Senpai, you’ll leave me too, won’t you?”

Her red, tear-filled eyes met mine. Her expression was so different from usual that I felt relieved her mask had finally come off.

“I can’t promise I’ll never leave.”

“I knew—”

“But even if I go somewhere, I’ll always come back.”

“Don’t just come back—don’t abandon me. Otherwise, I’ll be so anxious…”

“Alright. I promise I won’t abandon you.”

I lightly patted her head, and she squinted happily, then asked, as if to confirm, “Senpai! Senpai…”

“Will you always be my senpai from now on?”

It was a question filled with hope, fear, and everything she was. The reason she’d keep living.

“Yeah, I promise. You’ll always be my precious junior, Toa.”

“A lifetime isn’t enough. Even if we die and are reborn, we’ll still be senpai and junior.”

“That’s the plan.”

I held her hand and led her away from the shrine. She didn’t make a wish to the snake god or learn the three noble families’ secrets.

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

Toa was still scheming, teasing me whenever she got the chance, but through spending time with me and Mahiru, our house seemed to become her home. Now, she’s over almost every day.

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

*

Or so I thought.

“Senpai, talking to any younger girls besides me is a no-go, okay?”

“You’re my senpai. So don’t abandon me, alright?”

“Washing your back is a junior’s job, Senpai. Let’s make you feel really good, okay?”

Toa became a slightly possessive junior. Her closeness and frequent physical contact were downright bad for my heart.

Light touches were fine, but barging into the bath was a serious issue. If Mahiru hadn’t stopped her, who knows what would’ve happened…

Still, I was glad she opened up. Her beaming, genuine smile was far more charming than her usual scheming one.

And so, Toa Watarase was won over—and turned yandere.