"Aniki!"

The extended yell could be heard throughout the entire gymnasium as someone tackled Kageyama Tobio to the floor while he was mid serve. The entirety of the Karasuno volleyball team paused to watch as the first year struggled, pinned to the floor by an unknown girl with extremely long black hair that was pulled back into a ponytail.

"Oi, Ryuu, look at that!" Nishinoya whispered to his friend.

Tanaka nodded, "Kageyama's sister?"

Yamaguchi walked over to the two second years, "I think he's an only child?"

"Sei-Seishin?!" Kageyama shouted in confusion. "Seishin, get off," he said weakly, tapping the person on top of him repeatedly.

"Ah! Sorry!" Seishin exclaimed, climbing off of the boy.

As soon as they could see Seishin's face, quite a few of the club members began to realize that someone very attractive had just tackled their setter to the floor.

"Oi, oi, Kageyama!" Tanaka began to shout, "who's this?"

"Ah," The boy paused, "My cousin, Kageyama Seishin."

Said person bowed quickly, "Please call me Sei, nice to meet you."

"Sei-chan" Nishinoya blushed.

Seishin was visibly taken aback, "S-sei-chan?"

"Hey, Bakageyama! You didn't tell me you had such a pretty cousin," Hinata whined, walking over to the pair.

Seishin and Kageyama looked at eachother in confusion for a moment before looking back at Hinata.

"Hinata..." Kageyama began, "you do realize that..."

"Realize what?"

"That I'm a boy." Seishin interjected lamely.

A chorus of confusion sounded throughout the gym, save for Tsukishima and Kageyama, who both didn't care about Seishin's gender. The topic was quickly overstepped when Kageyama turned back to him cousin to talk to him.

"Aren't you supposed to be in Canada?" He asked.

Seishin hummed awkwardly, "well, we moved back, and now I go here." Kageyama's face froze as he waited for further explanation on why his practice was interrupted, "I wanna join the team."

Daichi stepped forward, "Sure, I'm Sawamura Daichi, team capitain, what position do you play?"

"Sei, you're from Canada?! What's it like being Bakageyama's cousin? Do you really play volleyball?" Hinata interrupted, suddenly excited by this new face.

"Hinata..." Asahi whispered, trying to let him know Daichi was talking.

"I play libero, Sawamura-senpai," Seishin smiled, completely ignoring Hinata.

"Ne, ne, Sei I-"

Kageyama interrupted Hinata by pulling at the collar of his shirt, "If you have time to ask questions go practice your recieves!" He shouted, pulling the protesting redhead to the other end of the gym.

Sugawara smiled at the scene and urged everyone to continue their practice, the only one who didn't listen was Nishinoya, who was interested in the new libero.

"Kiyoko," Daichi called, "can you get him a club form and a pen?"

"Sure," she replied and walked over moments later with the sheet and a pen.

"Thanks," Daichi smiled, "here you go, Sei, you can fill it out on the benches over there, just give it to Kiyoko when you're finished."

With that, Daichi walked away and over to Sugawara to practice. Seishin relaxed himself and began to walk over to the bench, smiling to himself about getting to see his cousin again. After all, Kageyama was someone he had always respected. He really wished he could have watched Kageyama play volleyball in junior high, but unfortunately he was living in Canada at the time. Before Seishin could make it to the bench, he was stopped by a short boy with a blonde streak in his hair.

"I'm Nishinoya Yuu," he said, "so you're a libero?"

Seishin eyed the boy up and down, noting that he was the one who called him Sei-chan before, Seishin flushed sightly, "yes, I do."

Nishinoya grabbed his chin and nodded, "Okay, okay, then I'll be taking you under my wing," he laughed triumphantly.

"Ah thank you, Nishinoya-senpai, I could use the help," Seishin smiled.

Nishinoya inwardly swooned at how cute his kouhai was, no matter if he was a boy, he was easy to mistake as a girl. Seishin's face was round and slim, his hair was long with bangs that framed his face, and he had long eyelashes too. When Nishinoya looked up for Seishin again, he had already scurried off to the bench to fill in his club form. He seemed to be writing extremely quickly and practically had the form in Kiyoko's slender hands in a matter of minutes. Nishinoya watched as Seishin bowed quickly to the girl and quickly ran over to Kageyama, grinning at him and asking to practice with him. The short libero shrugged, walking back to join Tanaka, who was practicing blocks with Asahi and Sugawara.

That day after practice, Hinata, Kageyama, and Seishin all walked home together.

"So why did you move back?" Kageyama asked.

Seishin looked over at Hinata and back to Kageyama before smiling awkwardly in response.

Hinata pulled in front of the two with his bike started to question Seishin again, "So you lived in Canada right? What's it like? Did you play volleyball there too?"

"Oi, dumbass-Hinata, one question at a time."

Seishin paused for a moment and then answered, "Canada's cold, but the summers are too hot. I did play volleyball there."

"Have you been playing long?"

"As long as Tobio," the boy shrugs.

Hinata nodded, "so how tall are you?"

"One seventy four centimetres."

"How long have you known Kageyama?"

Seishin pulled his eyebrows together in confusion, "uh... birth?" he said, like it was obvious.

"What are you asking such stupid questions for? Dumbass Hinata!" Kageyama barked at the short red head.

Seishin was the first to leave their group, having to take the bus home. As Seishin walked in the door he called out to his sister.

"Sakura? I'm home."

A girl with short black hair poked her head around the corner, "Sei-nii, welcome home. How was your first day?"

Thanks all for reading my work, I really appreciate it. Please comment, favourite and follow if you like it! Constructive criticism, theories, head-cannons, and suggestions are always welcomed and appreciated.

(Disclaimer: I do not own Haikyuu! or it's characters, only my OC's belong to me)

~ Chris