Yeon Woo navigates an awkward situation at her all-boys school where students talk about the Makgangpal heir's chest key, a mark supposedly revealed only by taking off shirts. Pressured to prove herself, Yeon Woo hesitates to change, drawing teasing from classmates who challenge her shyness and American attitudes. While others prepare for the mysterious heir's appearance, Yeon Woo plans to leave school once the heir is found. The episode ends with a stunned reaction as someone realizes Yeon Woo is a girl, highlighting her struggle to fit in and the tension ahead.