Pressage Flower countdown and Hanafuda aforementioned, he's also done a few guest pieces of her for magazines & official books. Hiroyama's been in the close circle of Type-Moon fans for a long time, even attending fan meetups hosted by the company. Supposedly there's even a guest piece he did of her for Fate/Stay Night back in 2004, but I can't find it if it's even online. He includes it in the omnibus of his doujins "KALMIA Archive" though, so it at least exists somewhere.