Who is Sensei's Uncle from Kokoro and what is their importance?

Sensei's mother asks his uncle to care for Sensei when she is gone. Sensei trusts his uncle to mange his fortune and family home while he attends college in Tokyo. His uncle, who is a businessman and former member of the assembly, is on the surface a trustworthy man. Over time, however, he begins to pressure Sensei into marrying his daughter. Sensei later learns that his uncle is keeping a mistress, and that his once failing business has been thriving for three years. When Sensei learns that his uncle has stolen much of his fortune, the reader discovers the event that changed the course of Sensei's life.