Itsuki is the biggest bastard and I love him. The two main characters really sold me on this manga, their interactions led the whole story and made it much more enjoyable. Yes I know that sounds pretty obvious but trust me..! Itsuki's constant flirting and Hisame's reactions made the whole series amusing and wanting more. Also the times where one of them would be in danger and the other's reaction warmed my heart, whether it be Itsuki's protective fixation for Hisame or Hisame's badly hidden care for Itsuki. If I had to say something critical of the manga, I'd say the lack of closurewith their relationship. But that's why sequel's exist and I have to keep in mind this is a shounen ai, so it doesn't bother me much.

If you want some historic youkai shounen ai in your life, I greatly recommend Toukaidou Hisame.