Kojo Kyoko's sudden arrival, although a headache for Chen Yu, became merely a minor episode in his life after Kyuuzai Ryousen properly settled her in.
In fact, for Chen Yu, the so-called service of Kojo Kyoko held little significance. He might indeed need some people to help him with tasks, but he required subordinates like Tsuchimikado Yoshiharu and Kyuuzai Ryousen, who could handle all sorts of trivial matters and stand on their own, not an ordinary kendo girl like Kojo Kyoko.
Though both are Transcendents, Kojo Kyoko is even a Formal Rank Transcendent which, theoretically, would make her significantly stronger than the two apprentices, Tsuchimikado Yoshiharu and Kyuuzai Ryousen.