Kaito Ran was only eleven years old when he stood by his ailing father's side and watched him suffer until he passed away. During his passing, Ran witnessed a djinn appear to take his father's soul to hell (NARAKU). Ran refuses, unable to accept his father facing eternal perdition, regardless of the djinn telling him that that was the order of things.
At the end of the day, his refusal meant nothing. His father was taken to hell, but during the process, Ran caught a glimpse of hell before the spiritual portal disappeared. He saw that it was a realm, a place of material and magic. He saw nine cities and towers, mythical beings and doomed souls. He realized that he could go there, he could go to hell and rescue his father.