Chosen as a vessel for the Fuga clan's god, a wind demon. After Kazuma returns to Japan, Ryuuya goes on a killing spree, murdering several members of the Kannagi branch families using wind magic, making it appear as though Kazuma was responsible.

Spoiler

After being fully merging with the Fuga clan's demon god, Ryuuya is killed by a combination of Ayano's crimson flame and Kazuma's contract invocation.