Responses
I doubt that the author was going to release a third volume because the first one is originally a one-shot manga, a single volume, then made a sequel to it 4 years later, due to the audience wanting more, and now it's been 4 years...no one really said if the author was going to make a third sequel to the manga.
I have very mixed feelings about the anime. The anime is great on its own, but I can’t help wondering how the story would have been handled if the anime had never been made and the mangaka hadn’t been harassed, and one day Volume 3 of the manga had been released. For example, maybe Hirose would have discovered his sexuality through the teacher, been rejected, and then bonded with Nakamura over that shared experience. The possibilities were endless, and there could have been so many other directions the story might have taken. Now, the chance of ever seeing those kinds of routes has basically disappeared.