Hana was enjoying her peaceful days at school until she received a mysterious letter which said: "Do not say a word."... She doesn't know what to do, thus she begs for help of her friends to find out who is the...

Ogino is a teacher who is being harassed by the students in her class. Ogino was an ideal teacher in the letters to Yoarashi, an absent student. However, Yoarashi, who came to school, knows that Ogino's letters...