Shiro Onijima is an antagonist in the anime and manga series Pupa.
Shiro was the former husband of Sachiko Hasegawa. He would regularly abuse her and his two children, and he always felt great pleasure from this. Eventually, Sachiko divorced him, and his children found themselves on their own.
As the manga continued, it's revealed that Yume herself is partially responsible for her father's brutality; upon impregnating Sachiko as an escaped monster, Shiro became suspicious of his wife, believing that she cheated on him while he was working outside of town for five years. While he was already abusive towards his wife, the abuse only grew worse due to his suspicions. Most striking, it's revealed that Shiro wasn't the one to give Utsutsu his scar; during one of Yume's rampages, she gave Utsutsu his scar. It's also revealed that she unknowingly made Utsutsu half-monster, which further explains his accelerated healing.
Sometime before the events of the manga, Shiro was an orphan who was raised by Maria's grandfather. Shiro was continuously stripped and tortured by Genjurou all for the sake of inspiration for his paintings. It's also heavily implied that Genjurou went as far as to conduct experiments on him, as inferred by his ability to beat up several nurses and doctors with minimum ease. Shiro came to the conclusion that him being abused by his adoptive father meant that he cared for him, thus sparking his "love is pain" philosophy. Eventually, Imari committed suicide, and he escaped.
Realizing that his son was half-Pupa monster, Shiro desperately tried to save his son, but he ultimately failed to do so. His son, upon transforming into his Emergence form, evaporates into butterflies with his beloved sister.
Shiro was a merciless man who believed that he was above the law. He took great delight in beating his loved ones, and he never felt a grain of remorse for it. He is also very self-centered and constantly referred to himself as the head of his household. However, as the manga was nearing its end, it's shown that Shiro truly does care for his son, though he displayed it in an unconventional way.
- Sachiko Hasegawa (ex-wife)
- Utsutsu Hasegawa (son)
- Yume Hasegawa (daughter)
- Genjurou Imari (adoptive father)
- Maria "Ai" Imari (cousin)
- Makoto Imari "Juuzou Hotoki" (cousin)
- Unnamed Onijima (mother)
- He is voiced by Kōji Yusa.