Class 3-D has finally reached their third year, but their unconventional teacher Kumiko Yamaguchi, known to her students as Yankumi, faces her greatest challenge yet: saying goodbye. The special episode Gokusen Special: Sayonara 3-nen D-gumi serves as both a sequel to the first season of the live-action series and a prequel to the second. The story follows Yankumi as she navigates the final days with her beloved homeroom class at Shirokin Gakuin, the all-boys private high school where she began her teaching career. Throughout the first season, Yankumi, who is secretly the heir to the Oedo yakuza clan, earned the respect of her delinquent students not through textbooks but through her unwavering belief in them and her formidable fighting skills, which she uses to protect them from genuine threats. The special brings closure to her journey with the original students of 3-D, including Shin Sawada, the class leader who discovered her secret; his close friends Youichi Minami, Haruhiko Uchiyama, Teruo Kumai, and Takeshi Noda; as well as her fellow teacher Shizuka Fujiyama. The narrative focuses on farewells as graduation approaches, with Yankumi reflecting on how much she and her students have grown since she first arrived as a naive teacher. The title Sayonara 3-nen D-gumi (Goodbye 3rd Year Class D) underscores this emotional conclusion. After the students graduate, the special sets up the transition to the second season by showing that Shirokin Gakuin closes its doors, forcing Yankumi to find a new teaching position at a different school. The episode thus completes the arc of the original class while paving the way for Yankumi to start fresh with a new group of troubled students, carrying the same principles of loyalty, justice, and tough love that defined her time with 3-D.