Hibiki (Suzu Hirose) agreed to help her friend Chigusa pass a love letter to Teacher Seiya (Renya Nakamura), but she accidentally put the love letter in the shoe cabinet of Teacher Ito (Toma Ikuta). Teacher Ito is a famous cold-faced killer in the school. He seems to have no emotions on weekdays, but Hibiki discovered his warm and kind side by chance. In fact, Ito also had an unforgettable love, but the end of this relationship was too tragic, which made him completely lose confidence in love. Hibiki gradually fell in love with Teacher Ito. She used her tenderness and innocence to melt the ice in Teacher Ito's heart, and the two finally confided in each other and began to date. However, Teacher Ito's cold attitude still made Hibiki often feel uneasy. Not only that, Teacher Ito's former lover Misaki came to Hibiki's school and became an intern teacher.