Kasen "Ibarakasen, Kasen Ibara, Ibaraki-douji" Ibaraki

About

Kasen Ibaraki, who also goes by the pseudonym Ibarakasen or just Kasen (spelled with different characters compared to her given name) is the main protagonist of Wild and Horned Hermit. She is a mysterious self-proclaimed hermit living in the mountains. Possessing an artificial arm and various special abilities, she can often be seen dispensing knowledge to Reimu Hakurei, Marisa Kirisame, Sanae Kochiya and others.

Kasen is kind and polite to nearly everyone. She is always willing to lend a word of advice or teach a lesson, but is often seen as preachy and overly critical of others.

She appeared to have two arms, however, when Reimu Hakurei seized her right arm, it bent flabbily and smoked leaked out of the gaps in her bandages. In Urban Legend in Limbo and Antinomy of Common Flowers, Kasen's artificial right arm contorts and uses the smoke within to attack. She needs to drink from the Ibaraki Box of a Hundred Medicines regularly so the artificial arm doesn't rot.

As of Wild and Horned Hermit Chapter 49 Part 2, Kasen rejoined with her actual right arm and returned to her true form as an oni. As a part of this transformation, actual horns burst from the buns on her head, destroying the headwear in the process. After having her arm cut off and resealed, Kasen's horns are shown to be visibly smaller.

Unknown to the public, long ago in the past she was actually a wicked oni. However, all her malevolence was contained in her right arm before it was cut off and sealed by Onikirimaru, and Kasen's arm was replaced with an artificial one.

(Source: Touhou Wiki, edited)