Aizu Otsukayama Kofun is a 4th-century keyhole-shaped burial mound (approx. 115 m) in Aizuwakamatsu City, Fukushima. Rich burial goods including numerous triangular-rimmed bronze mirrors — symbols of Yamato court authority granted to regional leaders — demonstrate that Yamato influence reached deep into the Tohoku region. Designated a National Historic Site.

4世紀中頃築造の前方後円墳。全長約115メートル。三角縁神獣鏡など多数の副葬品が出土し、大和王権との関係を示す。国の史跡指定。