As the teams prepared for their warm-ups, (y/n) seized the opportunity to carefully observe Date Tech's players. Meanwhile, the Seijoh boys had their attention fixed on the Karasuno team, showing particular interest in Asahi and Nishinoya. (Y/n) couldn't help but recall the conversation she had with Kiyoko on her first day, when the team had their practice match against Seijoh. At that time, Karasuno's lineup was not yet complete.

"It seems like it's not just new players on Karasuno's side," the Seijoh coach remarked, his eyes narrowing as he surveyed the opposing team. "There's also a new coach."

Curiosity piqued, (y/n) glanced over at the two older males who were closely observing her brother. Though she maintained a reasonable distance, she positioned herself strategically to overhear the conversations that would inevitably unfold among the Seijoh team during the upcoming game.

"I wonder what the new coach brings to the table," Oikawa mused, his eyes narrowing in speculation. "From what I've heard, Karasuno has been on the rise lately. Maybe this coach has something to do with it."

Kindaichi, leaning in to catch Oikawa's words, nodded in agreement. "Yeah, there's definitely something different about Karasuno this year. I'm curious to see how they'll perform against Date Tech."

Iwaizumi, ever the pragmatic voice, chimed in. "Well, they have a reputation for their powerful attacks and relentless defense. With a new coach and some fresh talent, they might pose a bigger challenge than we expect."

The conversation among the Seijoh players continued, dissecting the strengths and weaknesses of their upcoming opponents. Their voices were filled with a mixture of respect and determination, fully aware that victory would not come easily.

(Y/n) absorbed the snippets of discussion, contemplating the dynamics at play. The anticipation in the air was palpable, a fusion of excitement, nerves, and unwavering determination. It was a testament to the fierce competition that awaited on the court.

As the game drew closer, the chatter among the Seijoh players subsided into focused silence. Their gazes shifted from the Karasuno team to their own reflections, each lost in their own thoughts and mental preparations.

For (y/n), this match held significance beyond mere spectatorship. It was a chance to witness the culmination of weeks of hard work, dedication, and the evolution of both teams. Little did they know, this game would mark the beginning of a series of encounters that would challenge their perceptions, forge unlikely alliances, and ignite a passion for the sport that would shape their futures.

As the matches were about to commence, Kindaichi's keen eyes caught the attention of several players from the Date Tech team, but it seemed that their gaze was directed towards (y/n). Perplexed, he called out to her in order to draw her attention to the situation.

"Hey, (y/n)-san," Kindaichi began, his voice filled with curiosity, "why is Date Tech staring at you?"

Turning her gaze towards the individuals Kindaichi indicated, (y/n) furrowed her brows in confusion. It was the burly player from earlier, his intense gaze fixated on her.

"Oh, probably because I threatened to shove his arm up his ass," (y/n) nonchalantly shrugged, causing the boys beside her to gape at her in astonishment. "He was being rude, and so was that other guy. They should learn some manners!"

Oikawa, always quick to interject and seek (y/n)'s favor, chimed in, "The audacity! To speak rudely to such a sweet girl."

Slightly taken aback by the attention her actions had garnered, (y/n) clarified, "Well... they weren't rude to me personally, but they were disrespectful to my team. I couldn't just stand idly by and let it happen!"

Kindaichi's response held a tinge of jealousy as he muttered, "Must be nice for them, having you to back them up."

Caught off guard by Kindaichi's remark, (y/n) turned to him with a gentle smile, seeking to ease any feelings of resentment or envy that may have surfaced. "Hey, Kindaichi-kun, you know you can always count on me too, right? I'll back you up just the same."

Kindaichi's expression softened at (y/n)'s words, a hint of relief evident in his eyes. He nodded appreciatively, realizing that he was fortunate to have someone like (y/n) by his side, ready to support him through thick and thin.

The atmosphere around them grew increasingly charged as the teams took their positions on the court, their anticipation reaching a crescendo. The crowd buzzed with excitement, their cheers and chants echoing throughout the gymnasium.

Yet, amidst the cacophony, (y/n) found solace in the knowledge that she had formed bonds with her newfound friends. She understood that her presence meant something to them, offering a sense of reassurance and solidarity in the face of adversity.

As the first serve resounded, (y/n) refocused her attention on the unfolding match, determined to be a source of support not only for her brother but for her entire team. With each spike, block, and dive, she couldn't help but feel her own heart race in sync with the exhilarating rhythm of the game.

...

Having spent ample time with the Aoba Johsai boys, (y/n) deftly absorbed the information she needed about Date Tech. Karasuno emerged victorious in their first match without encountering significant challenges, leaving Hinata practically giddy at the prospect of playing another exhilarating match.

After bidding farewell to Oikawa, Kindaichi, and Iwaizumi, (y/n) hurried off to congratulate her team, her steps filled with purpose. She yearned to retrieve her assistant coach jacket, which would grant her the opportunity to contribute actively from the bench alongside her brother during the upcoming clash against Date Tech.

As (y/n) approached the Karasuno team, their faces flushed with excitement and pride, she couldn't help but smile. She extended her congratulations to each player, showering them with words of encouragement and praise for their exceptional performance. The air was charged with anticipation, and (y/n) could sense the unwavering determination radiating from each member of her team.

"I'm so proud of all of you," she exclaimed, her voice resonating with genuine admiration. "You've trained tirelessly for this moment, and it's incredible to witness your hard work pay off."

Her words resonated deeply with the players, their expressions brightening with a mix of gratitude and renewed motivation. (Y/n) knew that her role went beyond being a supportive sister. She was determined to be a pillar of strength, a voice of reason, and a source of unwavering support for the team she held dear.

With a renewed sense of purpose, (y/n) made her way towards the equipment area, where she retrieved her assistant coach jacket. The fabric felt crisp and professional against her skin, serving as a reminder of the responsibility she carried as a valuable member of the coaching staff.

As she buttoned up the jacket, (y/n) overheard snippets of conversation among the players, their eager chatter intertwining with nervous excitement.

"Did you see that block from Tsukishima?"

"Hinata's spikes are on fire today!"

"We've got to stay focused against Date Tech's formidable defense."

Listening attentively, (y/n) absorbed every word, knowing that understanding the team dynamics and the players' mindsets would enable her to provide valuable insights and support during the match.

Once the players had gathered for their pre-match meeting, (y/n) positioned herself beside her brother, a sense of shared purpose emanating between them. Keishin glanced at his sister, a mix of gratitude and determination reflected in his eyes. It was an unspoken acknowledgment that they were in this together, as siblings and as vital members of the Karasuno team.

During the meeting, (y/n) interjected occasionally, sharing her observations and offering strategic suggestions. The players listened intently, appreciating the unique perspective she brought to the table. Her presence brought a sense of calm amidst the pre-match jitters, as if she were a beacon of reassurance and guidance.

As the team took their positions on the court, (y/n) settled onto the bench, her eyes locked on the players. She understood that her role extended beyond the boundaries of the court. She was the voice that would uplift them during challenging moments, the unwavering support during moments of doubt, and the beacon of inspiration to remind them of their shared goals.

With her assistant coach jacket donned proudly, (y/n) prepared to immerse herself in the match, ready to provide unwavering support and strategic insights. She knew that the battle against Date Tech would be fierce, but she had faith in the unity and unwavering determination of her team. Together, they would conquer any obstacle that stood in their way and march toward victory.

...

The Aoba Johsai boys stepped onto their designated court, their eyes keenly fixed on the Karasuno players who were diligently warming up for their impending match against Date Tech. Suddenly, their attention was drawn away as they noticed their coach's wide-eyed expression, filled with utter shock. Intrigued, Iwaizumi, Oikawa, and Kindaichi were called over to witness what had caught their coach's attention.

As the three of them approached, their jaws dropped in disbelief. There, amidst the intense practice session with Nishinoya and Daichi, stood (y/n) wearing an assistant coach jacket—a striking display that instantly commanded their attention. A mischievous grin spread across (y/n)'s face as she glanced at her surprised comrades before strutting away confidently alongside her team.

"(Y-y/n)-chan is a coach!?" Oikawa exclaimed, unable to contain his shock as he stumbled back a few steps.

The Aoba Johsai coach, his astonishment evident, motioned Iwaizumi, Kindaichi, and Oikawa to join him aside. The rest of the team, sensing something significant had occurred, gathered around, eagerly awaiting an explanation for their coach's bewildered state.

Meanwhile, (y/n) continued to assist Karasuno in their warm-up routine while simultaneously observing the Date Tech team. The Aoba Johsai boys, their attention fixated on her, struggled to come to terms with the revelation. It was as if she had transformed from a spectator to a key figure within a matter of moments.

"I saw you three sitting with her earlier! Did you know she was their assistant coach?" the coach interrogated, his tone a mix of curiosity and mild frustration.

"No, coach! She said she was just observing. We had no idea," Iwaizumi responded, his voice still tinged with disbelief.

The other two nodded in agreement, their expressions mirroring their astonishment. They had unwittingly fallen prey to (y/n)'s clever ruse.

As the team absorbed the shocking turn of events, their eyes remained fixed on (y/n), who was now engaged in a conversation with her brother Keishin. Sensing their gazes, she turned to her brother, shooting him a withering glare.

"This is all your fault, Onii-chan. They keep staring at me!" (y/n) complained, her frustration evident.

Keishin smirked, thoroughly enjoying the situation. "Well, it means you did your job. Oh, and by the way, Kenta is making his way over there," he informed her, pointing in the direction of the Aoba Johsai boys.

"Eh!? Dammit!" (y/n) exclaimed, her exasperation growing as she hurried after her mischievous pup.

Meanwhile, Kindaichi grumbled as he relayed (y/n)'s words and actions to his friend Kunimi, who looked thoroughly perplexed. Iwaizumi and Oikawa, trying to help the first-year conceal Kenta from their coaches' view, approached the scene. However, their efforts proved futile as (y/n) swiftly scooped up the mischievous puppy, zipping him safely inside her sweater.

"Honestly, Kenta, you need to behave, or you'll be stuck outside," she scolded the adorable canine.

"(Y/n)-chan! You lied to us! You said you were just watching and taking notes for your sensei!" Oikawa whined, feeling betrayed.

"Huh? Well, I was, for the first match. Although I was also supposed to gather information on you guys, but you were too busy talking about Hinata and Kageyama," (y/n) replied nonchalantly, finishing her explanation. She then turned her attention toward the coaches, a hint of warning in her voice. "Also, for your information, the new coach you were grumbling about is my brother, so watch it. The Ukais aren't known for being nice when pissed off or insulted."

The coaches were taken aback, their shock deepening upon hearing the name 'Ukai.' Kunimi, unable to contain his curiosity, interjected, "You mean you're related to the coach Ukai, who keeps vicious crows for pets!?"

The revelation sent shockwaves through the Aoba Johsai team. Even the coaches were flustered, realizing that they now faced the challenge of not one, but two formidable Ukais coaching the Karasuno team. The elder coach stepped forward, attempting to regain his composure.

"Well, I must say, I'm surprised that a high school student is an assistant coach. How did you manage that?" he inquired, his voice filled with genuine curiosity.

"Well, I was the libero on the national champion team back in my home country, and I've been playing volleyball since I was a toddler. I'm a trained strategist, specializing in analyzing players," (y/n) explained confidently, revealing a glimpse of her expertise.

"In what way do you analyze players?" the coach inquired, intrigued by her claim.

"Um, well, I'm not sure if I'm allowed to demonstrate... Let me ask Onii-chan," (y/n) responded, turning around to seek Keishin's opinion. What followed was a series of peculiar gestures and whispered exchanges between them.

Responding with gestures and pointing of his own, Keishin seemed to encourage (y/n) to showcase her talent, with a mischievous glint in his eyes. Slightly reluctant, (y/n) turned back to the team, grumbling about her brother's childishness.

"Alright, fine. Show me your starting lineup. Don't worry, this won't be news to the Karasuno team. It's more of a party trick that tends to freak people out," she declared, her voice laced with amusement.

The seven Aoba Johsai players lined up before her, exchanging curious glances as (y/n) proceeded to walk down the line, intently observing each player. After a thorough examination, she returned to her original position in front of them and began pointing out each player individually.

"You, the wing spiker. The one next to Kindaichi is also a wing spiker. Kindaichi is a middle blocker, and so is the third-year next to him. Number 7 is your libero. Iwaizumi is a wing spiker and clearly your ace. Finally, there's Oikawa, your setter, and I'm assuming a killer server," she concluded, revealing her exceptional attention to detail.

The Aoba Johsai coach, still grappling with the extraordinary turn of events, muttered to himself, "Please tell me you three informed her of all this."

The three players shook their heads, admitting their failure to disclose such crucial information.

"Are you human?" the coach mumbled incredulously, unable to comprehend the series of revelations.

(Y/n), casting a dismissive glance at the coach, deemed his question utterly absurd, unworthy of a response. She redirected her attention to the Karasuno team, witnessing that the match against Date Tech was about to commence. A wicked grin gradually spread across her face, one that had become infamous among the players.

The Aoba Johsai team, nearly paralyzed by the sadistic aura emanating from (y/n), found themselves involuntarily retreating a step, their eyes widening in both fear and anticipation. As (y/n) turned back to bid them farewell, she offered a polite bow, ensuring that Kenta remained concealed within her jacket.

"Excuse me, I have to go make sure Date Tech is crying in puddles of their own sweat and shame. Good luck with your match," she declared, waving to the three astonished males she had grown acquainted with.

Seconds later, the Aoba Johsai players found themselves transfixed, their eyes glued to (y/n) as she unleashed a scathing remark directed at a certain blonde middle blocker.

"Tsukishima, you lazy ass! I saw that shitty receive! Just because you're warming up doesn't mean you can half-ass it! And Kageyama, stop scaring Hinata!" (y/n) screeched, her words echoing across the court.

"Yup, she's definitely an Ukai. Her grandfather was just as terrifying when a match started. The same evil smirk, too," the Aoba Johsai coach remarked, his voice tinged with a mixture of awe and trepidation.

"Coach, you're shaking," Oikawa muttered, noting the coach's quivering form.

"Terrifying," the coach admitted, his voice barely above a whisper.

The Aoba Johsai players, lingering in a state of disbelief, exchanged bewildered glances, unable to shake off the awe-inspiring presence of the Ukai siblings.