Kanna who usually enjoys being at the top of her class is outscored by one point on the first aptitude test of her high school career by the high-level kuudere/low-level dandere Yuu. Unlike Kanna, Yuu is naturally talented and couldn't care less about getting high scores, so she throws away her test immediately after after getting it. This incredibly bothers Kanna, who then in front of the class, scolds Yuu for throwing away her "symbol of how hard she worked". This gesture of kindness(??) causes Yuu to fall for Kanna. And of course, all unbeknownst to Kanna, who's all about herself anyway.
(Source: MU)