When the 5th Haikyuu!! episode came out, I saw lots of people who read the manga (me included) being confused over Hinata’s words to Yachi after he had a fight with Kageyama.
The anime subtitles go like this
while the manga goes like this
I did a little research and found out that there wasn’t anything changed in the anime — originally, what Hinata says is this: 初めて 友達 じゃなく 相棒 が 出来た気がしてたんだ
I’ve consulted my Japanese teacher, just did some thinking and came to conclusion that what he says is a mix of phrases from the subtitles and the manga translation.
If you translate it literally, it’s gonna be along the lines of “It’s not like he was the first friend I’d made, but I had a feeling that we could be partners.”
If you get the gist out of Hinata’s words, it pretty much goes: “It was the first time I felt like I had a partner (teammate), not a friend.” So “could” from the first phrase transfers into “like” here, because after the fight Hinata is shocked that Kageyama, of all people, refuses to give him a chance to grow and get better — most likely, he even feels betrayed. He doesn’t know what happens next between them yet, hence this uncertainty.
Also, I’d like to turn your attention to this:
Hinata didn’t have a proper team through his entire junior high — much less an actual setter to toss to him. Suga’s mentioned it, too — everybody takes the setter’s toss for granted, but for Hinata it’s something special. He only got to feel what it’s like — to be a part of the team with the same goals like him, to have a rival/partner, whom he learnt to trust at 100%, with the same burning passion like him to motivate him all the time — in high school, which is why he treasures it so much. And also why he suffers and cries after the fight on his way home — because that feeling, his partner was ripped away from him by their disagreements. Remember, he said before: “I don’t like it when we don’t get along.” And he owns his presence on the court to Kageyama, and his amazing toss, too, his brightness as a decoy — and now it was him to question, or rather dismiss his potential to grow further and get better. Sucks to be you, Hinata.
PS: when I asked my Japanese friend to help me out with this, she, not having any context, translated it as “It’s the first time I felt that I could make a “soulmate”, not just a friend.” When I explained things to her, she said that “partner” is definitely better, but I think I still earned myself a heart attack and a whole river of Kagehina tears.