Shiouji is the brilliant creator of the Ropponmatsus and of Kabapu's "mecha."
The anime constantly suggests that he is a lolicon, but the manga later expands on this to reveal a much more complex back story. Gojo's father, Tenmangu Shiouji, was lauded as one of the world's most foremost scientists, but vanished when Gojo was young. His mother, Miwa Rengaya, suffered a severe behavioral change after Tenmangu disappeared, becoming overtly sexual and showering affection on Gojo, imprinting on him a distorted perception of women. This perception was shattered when Gojo met his young cousin, Umi Rengaya, and was inspired by her purity and innocence. Unfortunately, Umi - who now works at Gojo's laboratory assistant and intern - is now eighteen years old, and lacking in the innocence of her youth, so Gojo seeks has turned his attention to other young girls in the hopes of recapturing that spirit of purity and inspiration.
Gojo, in fact, has become an eccentric genius with an affinity for little girls and a capability for creating bomb dismantling robots.

(Source: Wikipedia, edited)