The Shimada Clan was a family syndicate and a criminal organization. They were later subjugated by Overwatch in the absence of their master.
The Shimada Clan was established centuries ago; they are a clan of ninja with skills in martials arts, swordplay, and archery. Their power grew over the years, enabling them to build a vast criminal empire that profited from lucrative trade in arms and illegal substances. The clan lived in the beautiful city Hanamura.
When the leader of the clan at the moment, Sojiro Shimada, father to the brothers Genji and Hanzo, died suddenly, the older brother Hanzo took over the enterprise. As advised by the elders of the clan, he demanded Genji play a more prominent role than he had in the past. Eventually their disagreement grew to a head, Hanzo killed Genji in a violent confrontation.
Genji, however, was rescued from death and implanted with cybernetics by Overwatch. Already a trained assassin and martial artist, he worked with the organization to successfully bring down his former clan.
Hanzo, for his part, was beside himself, believing his brother dead. Though he had been raised from an early age to lead the clan, he defected and set off on his own before it was destroyed.