Someone called my attention to this, so I'll give some explanation regarding my translation of this chapter's title.
The title, in Japanese, is 交流戦後のスレイブ (kouryuusengo no slave)
交流戦 is usually used to refer to the
interleague play in Japan. That's why,
in chapter 9, Yuuki thought Kyouka was talking about baseball. I translated it as "exhibition games" back then to keep Yuuki's confusion understandable, but after a while I just translated it as "matches". A literal translation for 交流戦 without baseball and games in the picture would be "exchange battles."
後 means "after". So 交流戦後 is "after the exchange battles."
の ("no") is a multipurpose (but generally possessive) particle. In this case, it's sort of like how "Hangyaku no Ruruushu" is "Lelouch of the Rebellion".
So 交流戦後のスレイブ would be,
extremely literally, "The slave of the after the exchange battles." I translated it as "Postmatch slave" because it is short and means the same thing.
So I hope that explains it,
@criver @MavB_Ver