Toko & Honoki In Hawaii.

On December 1st, the first volume of She Cheated on Me with My Senior, So I’m Cheating on Him with His Girlfriend will be released by Kadokawa Sneaker Bunko!

Thank you all for your support.

As a token of my gratitude, I will be posting two side stories—one today and one tomorrow.

Please note: This story follows the Kakuyomu WEB version. It is not connected to the Light Novel (Bunko) version.

Timeline: This takes place between Chapter 1 and Chapter 2, while the Sakurajima family is spending New Year’s in Hawaii.

Waikiki Beach, where white sands stretch as far as the eye can see.

At the foot of a palm tree that provided moderate shade from the scorching sun sat a woman wearing a sky-blue one-piece swimsuit adorned with a rainbow pattern.

She had long black hair with a bluish tint, features that were exotic but not as sharp as a Westerner’s, a slender yet ample bust, and slender, elegant legs.

Almost every man passing by, regardless of race, found his gaze pinned to her for several seconds.

Her name was Toko Sakurajima. A second-year student at Joto University.

Right now, she was staring at her smartphone, smiling gently.

After scrolling through the screen for a while, she looked up, let out a small sigh, and gazed into the distance with nostalgic eyes.

“What are you doing acting all melancholic in the middle of Hawaii, Onee!”

The person who called out to Toko and approached her possessed beauty and a physique that rivaled her own.

The difference, however, lay in the younger girl’s long hair dyed nearly platinum blonde and her slightly flashy makeup.

She wore a tropical flower-print bikini with yellow lace.

Having just come out of the ocean, the water droplets dripping from her body were quite alluring.

Her name was Honoka Sakurajima. Though she was only a high school junior, her figure could already be described as perfectly developed.

“I’m not acting melancholic. But we come to Hawaii every year. I’m just past the point of getting all hyper about it,” Toko replied, sounding a bit defensive.

“Really? I bet you actually wanted to go on a New Year’s date with your new boyfriend. You were unusually reluctant about the family trip this year. Papa looked so lonely.”

Honoka sat down next to her with a smirk.

“I wasn’t reluctant… New Year’s in Hawaii is the only time the four of us get to relax together with Papa and Mama since they’re usually so busy. I think it’s precious time, too.”

“So, what kind of guy is this boyfriend you want to see so badly that you’d pick him over your precious family? You have a photo, right? Let me see!”

Honoka leaned in to peek at the phone in Toko’s hand.

“He’s my boyfriend, but we only expressed our intent to ‘date’ on Christmas Eve. We haven’t seen each other once since then because of this trip, so I don’t really have many photos.”

“‘Not many’ means you have at least a few, right? Don’t be stingy; show me. He’s the guy who stole you away from a hunk like Kamokura-san. I’m curious.”

Honoka pressed her face closer to Toko, her eyes wide with curiosity.

…Honoka won’t let it go once she starts. Besides, if she thinks I’m being secretive for no reason, it might just raise the hurdle for Yu-kun…

“I really don’t have a single proper photo of him. I only have one where I accidentally pressed the shutter…”

As she spoke, Toko displayed a photo on her phone: A picture of Toko and Yu facing each other.

Honoka’s eyes widened.

“This is the only photo you have? This guy is clearly trying to make a move on you, Onee!”

Toko hurriedly denied it.

“No, no! That was when we went for a drive. I slipped on the shore, and Yu-kun just caught me to support me. I must have touched the shutter button on the phone I was holding… it was just a total accident.”

“Hmm. But why did he have the camera app open in the first place?”

Honoka was still looking at her with suspicious eyes.

“I asked him to ‘tell me about what cute girls like.’ So he asked me out on a day-long date… and he took a lot of photos of me. He said that ‘I am most beautiful and wonderful when I’m just being natural.’”

Toko answered with a happy smile, her cheeks flushing. She cupped the phone in both hands as if it were a treasure.

On the other hand, the look in Honoka’s eyes as she watched her sister had grown sharp.

“His natural self is best? What a cheesy thing to say. Is that why all the photos look like they were taken from a stalker’s angle?”

“Yu-kun didn’t mean it like that. And while the photos were certainly sudden, I gave him permission, so it wasn’t ‘stalking’ or anything…”

Feeling slightly offended, Toko pouted.

Honoka peered at the phone again.

“But still, this guy…”

“Can you stop calling him ‘this guy’?” Toko’s voice gained an edge.

“Don’t you think this man is a bit… underqualified for you, Onee?”

“What do you mean, underqualified!”

“I mean, look at him. Kamokura-san was an undeniable hunk. When I showed my friends that photo of me, you, and Kamokura-san together, they were all like, ‘Wow, so this guy is going to be your brother-in-law? I’m so jealous!’”

“You’re not the one dating him, so it has nothing to do with you!”

It was rare for Toko to sound so emotional.

As for Honoka, the more Toko defended him, the more she began to dislike this “new boyfriend.”

“Well, maybe, but this guy is just so… plain. Compared to him, Kamokura-san had a real presence, even if he was a guy. He wasn’t just handsome; he had an aura.”

“There’s no need to compare Yu-kun to Tetsuya. Besides, Yu-kun is actually quite popular with the girls in his club!”

“I guess he’s above average. But he looks more ‘cute’ than ‘cool.’ Is that how he triggered your maternal instincts? Still, as a boyfriend, he’s a step down from Kamokura-san. I don’t think he’s a good match for you.”

Toko turned to face Honoka with a sharp glare.

“What’s with that attitude? Honoka, you’ve been acting really unpleasant!”

Honoka shrugged and held up her hands.

“Hey, hey. I’m just an unpleasant girl, I guess. But it’s surprising. I didn’t know you were so weak for that kind of pushiness, Onee.”

Just as Toko was about to say something more to her sister—

“Hey, are you guys Japanese? If you like, we can show you some great local restaurants.”

Two “local” men (residents of Hawaii) called out to them in fluent Japanese.

One had hair that was blonde almost to the point of being red; the other looked Latino.

“We know a great place for lobster and rum. Let’s go have some fun.”

As they spoke, the duo flanked Toko and Honoka, naturally reaching out to take their arms.

However, both Toko and Honoka shook them off.

While Toko glared at them, Honoka managed a forced smile.

“Sorry, we’re with our family. Our parents are coming any minute. Plus, we have plenty of acquaintances here and we’re meeting up with them. So we don’t need a guide or ‘local friends.’”

She waved them off with a “Bye-bye.”

The duo, sensing that further pursuit was useless since they were with family and local acquaintances, shrugged and walked away.

“That’s the tenth time since this morning. Don’t go thinking every Japanese girl will just follow you if you call out to them!” Honoka spat out in Japanese after they left.

Toko grimaced in displeasure as well.

Honoka turned back to Toko.

“So, what’s your precious boyfriend’s name?”

“Yu Isshiki. He’s a freshman at the same university and department, one year below me.”

Upon hearing that, Honoka’s face froze for a moment in thought.

“Yu Isshiki?”

“Yes. He went to the same high school as me, Kaihin-Makuhari High. Though we never interacted at all back then. We only started talking after he entered university and joined my club.”

“…Yu Isshiki.”

Honoka whispered the name again, as if confirming it.

“Is something wrong?” Toko asked, sensing her sister’s strange behavior.

“No, nothing. I just thought ‘Isshiki’ was an unusual name.”

“I suppose so.”

Toko stood up and brushed the sand off her hips and legs.

“Honoka, let’s head back to the hotel. I want to change and go shopping. Want to come?”

“Hmm, I guess so. You’re picking out a souvenir for your boyfriend, right? I’ll tag along.”

“Honestly!”

Toko gave Honoka a light glare, then turned on her heel toward the hotel.

They were staying at the Hilton Hawaiian Village Waikiki Beach Resort.

From there, it was less than a five-minute walk.

Watching her sister’s back as she walked ahead, Honoka thought:

…Yu Isshiki. One year below Onee means he’s two years above me. And if he went to Kaihin-Makuhari High, then he’s Meika’s…

Honoka recalled what her best friend since middle school, Meika Ishida, had told her.

“I’ve had someone I’ve loved for a long, long time. His name is Yu Isshiki-san. He’s my big brother’s best friend. But, Yu-san only sees me as ‘his friend’s little sister’… I wonder if I’ll always be in this position? I wonder if I’ll ever be his girlfriend.”

…The person Meika has a one-sided crush on is Onee’s new boyfriend…

Honoka felt a stir in her chest.

She got along well with her sister, Toko, and respected her as a serious and hardworking person.

But… Honoka also felt a trace of resentment toward her sister, who—intentionally or not—ended up taking everything for herself.

…To take even the person Meika loves… and doing it unconsciously…

To Honoka, being “unconscious” in this situation felt even more malicious than being “intentional.”

…I’ve decided. I will never let Onee and Yu Isshiki stay together. He’s not a good match for her anyway…

With that resolve, Honoka chased after Toko.