A/N Hey people! So, this is my first fanfic here. I'm aiming for something light and humorous, and I hope to have frequent updates (talk to my professors about that, though). If you'd like to beta, feel free to PM me, I usually answer quickly. Anyways, please review! And also, please don't flame me if you don't like it. Constructive criticism, people!

Disclaimer: Sadly, I do not own any of these fascinating stories. Harry Potter is the property of JK Rowling and whoever else lays claim to it, while Prince of Tennis belongs to Takeshi Konami. All I've done is put everything together.

And now for the fanfic (drumroooooollllllll, please!)

Harry looked up at his godfather in shock and disbelief. "Sirius, you're kidding."

"Ah, not really." Sirius gave his unamused godson a sheepish look. "Look, Harry, you know I wouldn't have kept it from you if I had known. I just found this out."

"I know, I know. But why do I have to deal with this now?" Knowing he sounded like a spoiled brat, Harry sighed. He'd survived a war, Voldemort, and Ron and Hermione's bickering, and this was his reward?

Okay, maybe he should start at the beginning. Although Sirius had fallen through the Veil back when Harry had been in fifth year, a spell from the Ministry had set him free. Turned out that Luna was right, the people in the Veil were just on the other side. Sirius had come back after the war with little damage and had immediately taken over Harry's life. Not that Harry was upset. He actually kind of enjoyed having a "parent" around, and Remus hadn't been the best substitute. He had Teddy, after all, and Tonks. So it was just Harry and Sirius (and Kreacher, if you want to be particular) in Grimmauld Place, with the usual visitors: Ron, Hermione, Remus, random Weasleys…

Since the previous year had been disrupted for all Hogwarts students, Professor McGonagall had decided to have the Seventh years repeat the year, making them "Eight years". She had chosen not to do the same to for the younger students due to the opinion of majority of the chairmen that they could catch up over the next year or so. Hermione had made Harry and Sirius crazy enough that Harry was going to be joining for that year.

What had sparked Harry's annoyance at his beloved godfather was in an innocent blue envelope on the table. It was a letter to Sirius about a cousin of his, one that "was half-decent, really". This cousin's family had moved to Japan years ago, just before the first Wizarding War, and now he wanted to send his son to Hogwarts. The cousin was a few years younger than Sirius and this child was his eldest. It seemed obvious (to the cousin, at least) that Sirius should take the boy in for the year, keep an eye out, just generally look out for him.

Now, had that been the end of it, Harry would have been okay. Not thrilled, but okay. But it wasn't. In order to "acclimate" the boy to England and other witches and wizards, the cousin wanted to send his son to Sirius for the summer. The entire summer. He figured that the boy was between semesters in school, so either he could transfer to Hogwarts if he liked the magical world, or he could just come back to Japan with no problems, schoolwise, at least. Sirius was ready to agree, since he wouldn't turn his back on one of the few relatives he liked. Well, tolerated would be the more accurate word. Heck, he was even starting to write to Narcissa Malfoy once in a while. A very long while, but he still wrote to her. Before he agreed, though, he wanted to get Harry's approval. The war had ended just a couple of weeks ago, and it was a raw time for everyone. Sirius wanted to make sure that Harry could handle it. Quite frankly, Harry wasn't sure what he could or couldn't handle, but he didn't want to upset his godfather. Still, it would take some getting used to.

"Fine. Go for it." Harry sank onto the couch and stared moodily at the plate of cookies Kreacher had placed on the table.

"Harry…"

"I'm fine with it. How old is he, anyway? Sixteen, Seventeen?"

Sirius sighed. "Ah, that's where you might get a little upset. Or happy, if you really are as big a fan of the Weasleys as you say you are."

Harry gave his godfather a confused look. "Huh?"

"He's fourteen. Just started his first year of high school in Japan. That's why his parents are willing to switch him," Sirius answered. "You can think of him as the brother Lily and James never gave you. Although I am surprised about that fact, considering-"

"I really don't need to know that, Sirius. Really." Harry sighed and slumped on the couch. "I'll deal with it. Nothing can be worse than killing Voldemort."

Famous last words.

Hope you enjoyed! Please review, I'm completely new at this!