Sakai Tadahisa

Sakai Tadahisa (Japanese: 酒井 忠尚, さかい ただなお) was a warrior of the Sengoku period. He was a retainer of the Matsudaira clan and governed Mikawa Province's Ueno Castle. He was the son of Sakai Yasutada and was an uncle of Sakai Tadatsugu. He had served the Matsudaira family since the time of Matsudaira Hirotada and was a senior retainer. After Hirotada's death, he served Matsudaira Motoyasu (Tokugawa Ieyasu's former name), but he also secretly colluded with the Oda clan.

In 1563, during the Ikkō-ikki incident in Mikawa Province, he betrayed Ieyasu, allied himself with the uprising faction, and holed up in Ueno Castle. However, when the uprising was suppressed and the punitive force attacked Ueno Castle, he abandoned the castle and fled to Suruga Province. Nothing is known of his later movements.