Sorry, should have specified. Yes, I meant this arrangement, along with his other works. Well, if that's the case then it's sure to be floating around out there somewhere then. Thanks.
Do you mean his music or the original song? If you mean the original, the name is Planetarian. It is part of the soundtrack of a visual novel. You might find it online yet. As for him, I think he released this in Comiket years ago. Or so I have heard.