Nickname: Arajirou (荒次郎)

Eldest son of Miura Yoshiatsu and last head of the Sagami Miura Clan. His father gave him Arai Castle (also known as Misaki Castle) in Sagami and handed the position of clan head to him in 1510. He was known as the 'brave warrior with the strength of 85' and fought against Houjou Souun, but he lost Okazaki Castle and Sumiyoshi Castle, and went to ground in the Miura Peninsula. He and his father held Arai Castle in a three-year siege, but the castle fell at last, and he witnessed Yoshiatsu's seppuku.

Yoshioki then charged out into the midst of his enemies and was killed, thus ending the Miura line. With his death the Houjou Clan achieved subjugation of Sagami.

Note: English sites seem to universally give Miura Yoshioki's name as Miura Yoshimoto, which the Japanese Wikipedia lists as a possible reading. It officially gives the reading as "Yoshioki", which is also used by Mirage.