Koichirou Tsuzuki developed multiple personality disorder from an extremely difficult and traumatic childhood. His father prepared him from a very early age to take over the Tsuzuki company, a brutal regimen that deprived him of a normal life. He was forced into daily study with multiple tutors simultaneously, a existence where failure was not tolerated and the assertion of his own will was unthinkable. The sole positive aspect of this period was his mother, who served as his only beacon of light. After his father left her for another woman, she took her own life. This loss caused Koichirou to withdraw completely, for he had lost the most important person in his life, a profound grief he was never able to process.

This severe trauma fractured his psyche into at least three other known, distinct personalities. These alternate identities include Jun, Ryuuko, and a manifestation known as the human-faced tumor. The condition is a profound dissociative response to the overwhelming psychological pain and utter lack of control he experienced during his formative years. The specific traits of each personality are a direct consequence of the different coping mechanisms his mind forged to survive his upbringing. The emergence of the human-faced tumor is a particularly physical and grotesque manifestation of his internal trauma and psychological fragmentation.