Purpose: This qualitative study explained the experiences of male adolescents who perpetrated school violence and understand which changes occur over time. Methods: Data were collected from June 2014 to May 2015 from 21 male adolescents who had perpetrated school violence and faced punishments, including forced transfers or special education. In-depth interviews and participant observations were conducted, with each interview lasting 45-100 minutes over 1-4 sessions. All interviews were audio-recorded and transcribed, taking 3-5 hours per session, with the transcripts reviewed for accuracy. Furthermore, member checks were conducted with the two participants for feedback. Meanwhile, data analysis followed Grounded Theory using open, axial, and selective coding while adhering to COREQ guidelines to ensure transparency and reflexivity. Results: A total of 87 concepts, 34 sub-categories, and 17 categories were derived. The core category was identified as “breaking out of the emotional pain.”The basic psycho-social processes experienced by the male adolescents who had perpetrated school violence appeared in four phases; "eruption", "habituation", "separation," and "reflection." The central phenomenon was “explosion of repressed emotional pain.” Conclusion: This study provides novel insights into preventing school violence by providing a comprehensive understanding of the experiences of male adolescents who perpetrated acts of school violence. Crucially, it suggests that both assailants and victims of school violence should be looked after by their families, schools, and communities.