Nozomi Kuroda is in the 2nd grade of high school. One day, she finds a letter in a classroom desk. The letter has only the word "like" written on it. The person who wrote the letter is Jun Setoyama. He happens to be the most popular boy at the high school. Nozomi Kuroda feels embarrassed, but she eventually leaves a reply in a shoe closet at school. This is how their secret exchange diary begins. Nozomi Kuroda soon learns that the intended recipient for the first letter was her best friend. Nevertheless, Nozomi Kuroda is attracted to Jun Setoyama, who expresses his thoughts and feelings unlike her. She's unable to tell him the truth that the person exchanging messages is her and not her best friend.

Fifth grader Kei Watanabe has inherited the hunter's blood to hunt yōkai. To save the world from destruction, Kei challenges a war against the yōkai.