I'll admit I'm really not sure what to do when tagging images like this. There's nothing that directly indicates hatsuzuki is the artist's hatsu-kun, but almost all of their drawings with hatsuzuki feature him, at the very least according to the commentary. But this time there's absolutely no mention of it. Some of the twitter replies do use 初くん though. For now I'll stick with that assumption based on the artist's previous works.