The 13 Lords of the Shogun S01 E05 Ani tono Yakusoku (兄との約束)

Following the ascension to power of Taira no Kiyomori, the Minamoto clan is exiled. Minamoto no Yoritomo meets Masako, the sister of Hōjō Yoshitoki and later marries her. Following this marriage, the gears of Yoshitoki's destiny begin to turn.