Sometime after its creation, Urahara sought a means to destroy the Hōgyoku, though all attempts proved to be ineffective. Out of desperation, he sealed it and placed it within the depths of a person's soul (Rukia), though the exact date he did this was not stated in the story (it was long before the start of the story as proven by Aizen's comments to Ichigo recently). How he did this is not explicitly stated, but it could have been using the same device that Aizen used to remove the Hogyoku from Rukia at the end of the Soul Society arc. Then, the night of the first chapter, the very start of the series when Rukia initially lost her powers and Urahara offered her a Gigai. The Gigai stopped her from regaining her powers. His intention was that Rukia would become a normal Human and have the Hogyuku inside her forever.