Kylie was among the children picked for training as the Empire's assassin. Since he lacked the necessary skills naturally, he had to be given performance-enhancing drugs. Kylie was a cheerful person who saw the bright side of things. He showed concern for his comrades and was very happy to see Kurome again. At some point he became the leader of the Dark Squad. The Dark Squad was called by Honest to assassinate people of the Revolutionary Army.

Spoiler

Kylie and his group tried to fight the Revolutionary Army but they were intercepted by Akame. She easily slaughtered The Dark Squad. Kylie used a new drug and fought Akame. She was still stronger and killed him. When he died he said, that although he didn't like the Top Seven they really were beasts. He demonstrated the ability to use two swords simultaneously in battle and although he was strong, he was no match for Akame.