Career
Kiyoyasu was the grandfather of the exceedingly famous unifier of Japan, Tokugawa Ieyasu. Kiyoyasu soon gained control of the whole of the northern region of Mikawa Province after the Saigo clan had surrendered after four generations of conflict between the two clans. The Okazaki Castle was also built as a monument towards the Matsudaira"s power.
However, certain hatred began growing within a certain retainer of Kiyoyasu"s, a retainer by the name of Abe Masatoyo.
During the year of 1535, this certain retainer had somehow sneaked into Kiyoyasu"s secret chambers and slew him with his Muramasa blade. Thus followed the Battle of Idano, and peace returned to the Matsudaira, Matsudaira Hirotada, father of Ieyasu, would succeed to the throne of power within the Matsudaira clan.
Another version of Matsudaira Kiyoyasu"s death has been told by the author A. L. Sadler:
So Kiyoyasu set out against this province. But if this was not done, and he was put to death on suspicion, he impressed on him the need of his continuing to serve their lord faithfully as if nothing had happened.
Just after this Sadayoshi"s horse began to be restless and kick out, and there was some confusion, and Kiyoyasu came out and gave orders to catch it and tie it up.
Hearing the noise, Yashichi at once concluded that his father was being arrested and was in danger, and without more Ado rushed out on the spur of the moment without any reflection and cut Kiyoyasu down. He was at once killed himself, but that did not save Kiyoyasu, who was only twenty-five.