The Spread Shot of Ibaraki-Douji's Arm from the world reborn (a Touhou LW original). She attacks with the icicle blade that Takemikazuchi used to defeat Takeminakata. Kasen Ibaraki is a hermit following the path of Heaven. The best way for Kasen to extend her reach is to use her arms. According to outside world data, a human warrior cut off Ibaraki-Douji's arm in the Heian era. She is that arm.

The Focus Shot of Ibaraki-Douji's Arm from the world reborn (a Touhou LW original). She attacks with the lightning blade that Takemikazuchi used to defeat Takeminakata. Multiple outside world records speak of Ibaraki-Douji's past, but the most notable theorize that they came from either Echigo or Settsu. However, this seems to contradict the theory that the oni of Mount Oe were descendants of the ancient Taniha kingdom that was founded by an ocean-faring people. Others speculate that the concept of oni originated from pirates, so perhaps this theory shouldn't be discounted so quickly.

A Spell Card of Ibaraki-Douji's Arm from the world reborn (a Touhou LW original). She attacks with the sword Takakuraji received from Heaven. According to the Echigo theory, when Ibaraki-Douji was little, they were taken in by a shrine to the god Ame no Kaguyama. Ame no Kaguyama is said to be the deification of Takakuraji, a human who received the divine sword, Futsu no Mitama, from Takemikazuchi, and later presented it to Jinmu, the legendary first emperor of Japan. It's possible that this is the same sword that Takemikazuchi used to cut off Takeminakata's arms. This is backed up by the fact that the sword, Futsu no Mitama, is a god in its own right, called Futsunushi, who traveled with Takemikazuchi and the ship god Torifune. This trio of gods, centered around Takemikazuchi, can also be interpreted as a single god of war with three aspects. Futsu no Mitama was supposedly enshrined in Isonokami Shrine, which was run by the Mononobe clan. However, the sword itself is said to be stored in Kashima Shrine, which was dedicated to Takemikazuchi following the terrible earthquake that occurred during Prince Shoutoku's regency.

A Spell Card of Ibaraki-Douji's Arm from the world reborn (a Touhou LW original). She attacks with a mythical text that was supposedly lost in a fire. As Ibaraki-Douji was taken in by a shrine, so was Shuten-Douji taken in by a temple. Apparently, they were sent there because their incredible good looks were becoming a distraction to members of the opposite sex... though that's probably an embellishment to the story that was added by later generations. Even though oni are supposed to be embodiments of evil, they are often romanticized in tales and legends. It's like the Japanese version of a picaresque novel. However, the part of the tale where both Ibaraki-Douji and Shuten-Douji become oni due to cursed love letters written in blood does seem a bit overly dramatic. Then again, the fact that this bizarre yet romantic tale has endured so long is surely a testament to its timeless appeal.

The Last Word of Ibaraki-Douji's Arm from the world reborn (a Touhou LW original). She re-enacts a hazy memory from her past. There are infinite ways to interpret the events of Ibaraki-Douji's past, and what follows is but one of them. Cursed love letters written in blood transformed the handsome Shuten-Douji and Ibaraki-Douji into oni. However, this curse did not originate from feelings of unrequited love toward them. That was merely the vehicle through which a much older and more powerful curse traveled. The ancient sword Futsu no Mitama had a wavy blade, reminiscent of a snake. The god Takemikazuchi used it to cut off Takeminakata's arms, turning the other god into an armless serpent. In return, Takeminakata cursed the sword that cut him. The sword was then gifted to Takakuraji, who presented it to Jinmu, the first emperor of Japan. However, not wanting to curse the emperor, Takakuraji kept the curse with him, which later passed to his shrine when he became a god. This was the same shrine where Ibaraki-Douji lived as a child, and when they became an oni and got their arm cut off, the curse came full circle. It's possible that the bloody love letter Ibaraki-Douji received was written in Jindai Moji (characters from the Age of the Gods), similar to a lost text supposedly written by Prince Shoutoku. There are also theories that the first Night Parade was performed by the ghosts of the prince's descendants. This might also explain why Kasen turns into a snake when hit by Mamizou's Transformation: Futatsuiwa Clan's Curse Spell Card.