Manga are Japanese comics with diverse genres and demographics, one of them is shonen. Oyasumi Punpun by Inio Asano is a slice-of-life manga that explores psychological depth through its protagonist, Onodera Punpun. This study analyzes the symbolic meanings behind Punpun’s various forms and how they reflect his inner states. The contrast between Punpun and other characters intrigued me and led to my interest in the symbolism of his changing forms. Using Erikson’s Psychosocial Development Theory, Punpun’s growth is categorized into three stages: school age, adolescence, and young adulthood. Semiotics is also applied to examine the connotations, denotations, and myths behind each of his forms. The findings show that Punpun’s eight forms mirror his inner struggles. In childhood, his simple form reflects innocence and dependency. In adolescence, three forms appear: a modified bird-like figure symbolizing struggles in self-expression, a tetrahedron showing self-isolation, and a bird-headed humanoid representing identity confusion. In young adulthood, Punpun shifts through four forms: a four eyed humanoid reflecting self-consciousness, a cylindrical head symbolizing shame and desire, a horned version expressing rage, and finally, a human head that signifies acceptance. These transformations reveal how manga can powerfully portray psychological depth and emotional growth.