Kusatta Kyoushi no Houteishiki  

Bad Teacher Equation, KKH, 腐った教師の方程式, Rotten Teachers Equation

Atsushi Arisawa enrolls at Jougaouka High School with the intention of being close to his childhood crush, Masami Shibata (Ma-chan). However, unbeknownst to him, Masami no longer works at the school and is replaced by her brother, Masayoshi, who is now the nurse. Atsushi mistakenly believes that Masamis personality has undergone a complete 180 and is horrified because he perceives it as being completely different from what he knew before. To make matters worse, his friend Kouji Inagaki is constantly trying to make out with him, making Atsushis life at Jougaoka High School unbearable. Despite this, Atsushi begins to think that perhaps the new Ma-chan isn't so bad after all and that maybe he actually likes her new personality. However, his happiness is short-lived when he discovers that Masayoshi is not Masami.