桐山 鯉

Koi is a butler of the Kuki Family. He was given the task to look around the world, and searching for people with overwhelming skills.

He was the one who scouted Tsubame when she was fighting with Gail Caracal and his brother (Gates supports his brother with the information on his laptop). Koi convinced Tsubame's father (Hisanobu Matsunaga) to transfer her daughter to Kawakami Academy, and made the name of the Matsunaga Family world known.

He also told to Tsubame if she goes to Kawakami Academy she will meet with a lot of stronger people, and even stronger than her. Later he was added to the squad who has to watch for Monshiro Kuki.

Koi is ranked number 42 between the butler and maids of the Kuki Group.