Ibaraki-dōji

upright|thumb|"Rōba Oni Ude wo Mochisaru Zu" (Depiction of an Old Woman Taking Away the Oni's Arm) from the Shinkei Sanjūrokkaisen by Tsukioka Yoshitoshi. It depicts Ibaraki-dōji shapeshifting into the form of Watanabe no Tsuna's aunt in order to steal back the arm. Ibaraki-dōji (茨木童子 or 茨城童子 "Ibaraki child") is an oni (demon or ogre) featured in tales of the Heian period. In the tales, Ibaraki-dōji is based on Mount Ōe, and once went on a rampage in Kyoto. The "Ibaraki" in his name may refer to Ibaraki, Osaka; "dōji" means "child", but in this context is a demon offspring. Ibaraki-dōji was the most important servant of Shuten-dōji.

As for the birthplace, there are theories that it may be Settsu Province (Mio, Ibaraki, Osaka, and Tomatsu, Amagasaki, Hyōgo) or Echigo Province (Niigata, formerly Tochio, now a settlement in Karuizawa, Nagano). Ibaraki-dōji had teeth since birth, and was feared for being a giant. After they became an oni, they met Shuten-dōji and became his subordinate, and together they aimed for the capital. Their gender is ambiguous, in some stories Ibaraki is a kijo (female oni), and in others a male. The female version is theorized to be Shuten-dōji’s lover, son, or his son's lover.