Complex sentence: Yuki Nagato is a bibliophile humanoid interface (created by the god-like figure called the Data Integration Thought Entity) whose responsibilities involve monitoring Haruhi and the investigation of an unexplained "explosion of data" three years prior to the present story.
Split into simpler sentences: Yuki Nagato is a bibliophile humanoid interface that was created by the god-like figure called the Data Integration Thought Entity. Yuki's responsibilities involve monitoring Haruhi and the investigation of an unexplained "explosion of data" three years prior to the present story.