Akaba (赤羽), born Masaru Ooyama (大山 勝, Ōyama Masaru), is a member of Kazumi Sawatari's Hokuto Sanbagarasu who transformed into the Castle Hard Smash (キャッスルハードスマッシュ, Kyassuru Hādo Sumasshu), and later the Castle Hazard Smash (キャッスルハザードスマッシュ, Kyassuru Hāzado Sumasshu).