​Yosugara Hikaru and his childhood friend Mioto have always had a close bond, but Hikaru has been secretly in love with her. Things become complicated when Mioto’s brother, Hakurou, and Hikaru’s sister, Akimi, also develop feelings for each other. One day, Akimi accidentally catches Hikaru in a compromising situation, leading her to demand that he separate Mioto and Hakurou. Reluctant at first, Hikaru is forced to give in to Akimi’s demands when she threatens to expose his embarrassing act. In a moment of anger, Hikaru becomes intimate with Akimi, who is left shocked and traumatized. Realizing the severity of his actions, Hikaru reluctantly agrees to cooperate with Akimi as long as their secret remains hidden.​