Though they aren't seen interacting much in the anime, Akoya and Ibushi seem to be on great terms with each other, Ibushi even going as far as to call him by his first name. In the manga, Ibushi can occasionally be seen teasing Akoya at times, against Akoya's wishes. In the Otome game, when Ibushi's seen going on his date with the protagonist, Akoya comes along to "steal" her away, at least in Ibushi's perspective; his true intentions are unknown.
Ibushi serves as a butler to Kinshiro; always making sure to be completely and utterly loyal to him. Though Kinshiro tends to act coldly towards him, Ibushi serves him nonetheless. It's possible that along with loyalty to him, Ibushi has a crush on Kinshiro.
They aren't seen interacting much in the anime. In the manga, however, Ibushi spits his drink out upon hearing Atsushi call him "Ibu-chan."
The two seem to be friendly with each other, occasionally interacting in both the manga and Otome.