MAL listed him as the only staff (aside from the music-making), so I guess that's about right. Unfortunately, I'll have to be a cheapskate and watch the fansub version, which I can do today. Dx
It's the film that put Makoto Shinkai into the spotlight. It was a complete one-man project (well, him and his wife). They even did their own voice acting for the initial version (it's in the DVD extras if you have the English DVD)