The Gemini Which is a Liar

Rin and Aoi are twin brother and sister and are very close. Aoi is popular in her school's kendo club, while Rin is popular with girls due to his fashion sense. When an old acquaintance on a rival kendo team appears and defeats Aoi-chan, and then shows romantic interest in her, Rin feels strangely jealous! Aoi doesn't understand Rin's behavior, and doesn't realize that Rin knows something about her that she doesn't...