Haruka Suzumiya (涼宮 遙)
A shy, timid girl who is friends with Mitsuki who introduced her to Takayuki, whereupon they fall in love with each other. Her hobbies are collecting picture books. She is involved in a serious car accident and ends up in a coma. The main part of the story starts when she awakens three years later.
Mitsuki Hayase (速瀬 水月)
Mitsuki is friends with both Takayuki and Haruka, but secretly she desires Takayuki. In high school, she was a strong swimmer and tomboy, but shortly after Takayuki and Haruka's relationship begins to develop, she grows distant and decides to quit, eventually leaving the swimming world altogether. She throws herself at Takayuki when he fails to climb out of his depression, and reveals her feelings for him. Mitsuki is well-meaning, but suppresses her feelings, allowing them to bottle up and explode in dangerous ways. Mitsuki also believes that she is responsible for her friend's accident, as she was the main reason why Takayuki was late for his date with Haruka.