Nezu Dohachiro is the science teacher of Tsuna, Gokudera, Yamamoto, Kyoko and Hana. He seems to believe that tests are the most important thing and always reminds his students that tests will always appear and that they have to be ready for them. He also dislikes students who get low scores, like Tsuna, and hates students who, despite not putting much effort, score high, like Gokudera.