Kokubanchi Sensei, named after the Japanese word "kokuban" for blackboard, teaches at Dream School. He possesses a blackboard-like head, a yellow body, and a tuft of blue hair. His green face features blue eyes with white plus-sign pupils, an orange beak-shaped mouth, and white division symbols on the cheeks. He prominently wears a card displaying the equation "E=mc²", signifying the principle of mass-energy equivalence.

He consistently displays a cheerful and energetic demeanor while interacting with students, maintaining a youthful outlook in his professional role. This character first appeared in the episode "Appearance! Yumemitchi and Kiraritchi", counted among the initial faculty members Mametchi and his friends meet upon arriving at Dream School.