Ōika (大イカ Ōika, lit. Large Squid) or Daiō-Ika (大王イカ lit. great king squid, meaning Giant Squid) is a squid yōkai or a giant squid that serves Han-Gyojin and appears in the GeGeGe no Kitarō series. In the 1996 anime it is named Yōkai-Ika (妖怪イカ Yōkai-Ika).
In the 1971 anime, the Ōika is a giant gray squid with eight long arms, prominent suckers, and a long mantle with triangular fins. A pair of eyes with white sclerae and black irises sit just under the mantle.
Within the 1996 anime, Yōkai-Ika is a giant white squid, having eight long arms, each with small suction cups, a thin siphon that rests between its eyes, and a long mantle that has spade-shaped fins at the side of the tip. Its eyes have yellow sclerae with red irises and a lack of pupils. After Kitarō possesses its body, its irises become green and the black-and-yellow pattern of the Chanchanko covers most of the mantle.
In the 2018 anime, its general appearance resembles more of a colossal squid while it is noted to be a giant squid.