If Chino defeats Chiya at chess, her prize for winning is for Cocoa to call her big sister. Cocoa, in the distance, asks why she’s being dragged into it. (Cocoa received being dragged in by Chino.)

ココア：

「なんで巻(ま)き込(こ)まれてるの!?」

巻(ま)き込(こ)む‘s negative stem is 巻(ま)き込(こ)ま. Append れる for 巻(ま)き込(こ)まれる.