Seasonal uniform change contest with 勝負

Vocabulary Explanation:

Nishikata arrives at school wearing his winter school uniform. He finds Takagi still wearing her summer uniform. Nishikata’s reason for the switch is that he heard the weather forecast for cooler temperatures. Takagi laments her carelessness.

高木(たかぎ):: 「同(おな)じタイミングで衣(ころも)替(が)えできたら私(わたし)の勝(か)ちって勝負(しょうぶ)してたのに。」; “We had a contest going where if we switched uniforms at exactly the same time, it would count as my win.”; Literal: “Even though we were having a contest where, if we managed to do the seasonal uniform change at the exact same timing, it would be my win.”
西片(にしかた):: 「勝手(かって)に！？」; “You just decided that on your own!?”; Literal: “On your own!?”

Key Points

1勝負してた uses the noun 勝負 as a verb

勝負(しょうぶ)する means to have a contest that decides a winner and loser, and してた (from していた) shows the contest was already underway in Takagi’s mind.

2できたら sets the contest’s winning condition

同(おな)じタイミングで衣(ころも)替(が)えできたら states the condition: if they managed to switch uniforms at the same time.

3って marks the rule Takagi made up

私(わたし)の勝(か)ちって quotes the terms of the contest: meeting the condition counts as her win.

4のに expresses Takagi’s disappointment

Ending the sentence with のに conveys her regret that the contest fell through when Nishikata switched first.

5勝手に protests a one-sided decision

勝手(かって)に means doing something on one’s own without consulting anyone; Nishikata never agreed to this contest.