"Basically, I'm just another of Kanzaki Nao's belongings"
An idle turn of phrase, generated off the cuff to halt further objections to his interference in a game that Nao Kanzaki would otherwise lose badly. It's otherwise meaningless in a way obvious to all present.
Yet, it makes him uneasy.
How many times since has he longed to rest his head on her knee, or take her hand in his and lay a kiss of loyalty upon it, and pledge himself to her ends? Too many. The bluff has come true. Or perhaps the truth was there, disguised, the whole time.