亜樹 直 Agi Tadashi is a Japanese manga storywriter, novelist and screenwriter. His original name is Shin Kibayashi (樹林 伸 Kibayashi Shin). He was born in 1962 in Tokyo, and graduated from Tokyo Metropolitan Musashi Senior High School and Waseda University School of Economics & Political Science. The penname "Tadashi Agi" is shared with his sister. Under the name Yuma Ando, he received the 2003 Kodansha Manga Award for shōnen for writing Kunimitsu no Matsuri.
The main mystery in this volume is a fun one. Closer to a standard "cozy mystery" than most of the earlier ones. And the blatant fan-service in earlier volumes isn't quite as evident in this one.
In nine volumes, they've made very little progress with the sub-plot of Himuro's back-story, but it looks like they plan to address that in the final volume.