With a beautiful vision of high school teaching life, new teacher Kumiko Yamaguchi (played by Yukie Nakama) joined the 30th anniversary of the founding of Platinum Academy High School, but was assigned to the dreaded 3rd year D group of the bad class as a tutor. The students who disobeyed discipline took turns to intimidate Kumiko, trying to scare away this inconspicuous new teacher. Kumiko didn't think so, and wanted to actively get closer to everyone. Her calm response also attracted the attention of the core figure of the class, Sawada Shin (played by Jun Matsumoto). It turns out that Kumiko's true identity is the fourth-generation heir of the Yakuza gang! Although the actual teaching life deviated from her expectations, and unexpected troubles appeared every day, the hidden Kumiko still chose to believe in her students and worked hard to lead them to the right path to achieve the goal of all graduating smoothly. This drama is adapted from the work of the same name by Japanese cartoonist Keiko Morimoto.