Seeing as they had hardly interacted in the past, the bluette's gentle manners had truly been a surprise for him, her apparent consideration for her friend being perhaps the unexpected aspect of it all. Remarkable people tended to be -or become- conceited or difficult to approach at some point and in some way, but no matter; these pointless musings weren't of any use right now. "You're such a nice friend, Sayaka-chan," he conceded, eyes narrowing as his smile widened, if only slightly. "I will, thank you."
If Sayaka saw his words as a challenge, the situation was barely a routine exercise for Oikawa-- which of course, didn't belittle the fact that he was being sincere nonetheless. His social skills were anything but top notch, and yet he knew how to behave way more correctly around females, even if his womanizer side also left much to be desired. But in any case, the only place in which he was to find a challenge was the volleyball court, and not exactly with a pretty girl like her.
The brunet blinked, features visibly softening just as an eyebrow raised in a discreet manner. "Ah?" It was only natural to assume that her being popular would make it all the more easy to socialize, and that was what he had done from the beginning and up until now. Such were the perks of being a well-known person, right? At least, that was what he was used to... when he looked past the comments regarding his nasty attitude towards certain matters. "Even so, feel free to come talk to Oikawa-san whenever you want. You know, I'm not gonna eat you~"
At the comment about being the first one she ever sent a letter, he giggled. It was understandable how her career as an entertainer would keep her away from things fit for people their age, though. "Whoa, lucky~ I hope you really do keep your promise!"
A sweatdrop rolling down his temple, as well as her taking a step back, reminded Oikawa what a pain those moments between the end of practice and making his way back home were. Still, her voice kept him away from such thoughts. Easy peasy, no rushing there. Sayaka had openly implied she would be okay with them talking more, so there was no need to be pushy now. With a nod, he was about to see her off when Well, that was an unpleasant turn he hadn't expected the conversation to take.
A breathy chuckle was held in at the back of his throat, brown hues diverting to the side. He barely had a clue they even had homework to do for that subject today. "Ah... I'm afraid not." Trying to recall the question numbers was useless, he knew that much. However, there was something to her speech that caught his attention. Good at languages, huh? He could use some help with that-- actually, with many things, but maybe it was best to go step by step first.
His eyes back on her, Oikawa's expression brightened as he put his good kid facade back on before keeping silent for just a couple seconds. "Say, Sayaka-chan, would you help me with that sometime when you're not busy?"