Ibaraki-Douji's Arm

Abilities: Super Strength(As an oni, Ibaraki-Douji's Arm possesses incredible strength, able to break the entire floor and making it explode with a single punch, generating a shockwave strong enough to send Reimu flying. She relies on sheer brute force. Reimu notes that there is no beauty in her attacks. Despite only using her right arm to do all the fighting, her strength is more than enough for Reimu to call her ridiculously powerful.), Control Undead(Ibaraki-Douji's Arm is capable of animating and controlling the skeletons of people she's eaten to do her bidding. The skeletons are able to reform themselves even after being blown away by Reimu. It's unstated if this is an ability inherent to her or some sort of magic spell. She also summoned a huge pile of skulls by throwing a single one of them into the air; the combined weight of the pile of skulls was great enough to break the ground by crashing into it.), Others(She uses stone pillars to attack Reimu from afar and disrupt her barrage of ofuda. She seemingly gathers them from the ground while floating, and without touching them, but the actual means are unknown.)

Personality: Kasen's malevolence was contained in her arm before it was severed from her, eventually becoming its own entity(which is Ibaraki-Douji's Arm). As her title suggests, Ibaraki-Douji's Arm appears to be purely evil. She had every intent to kill and eat Reimu, even implying that she'd use her reanimated skeleton as a servant. In the same instance, she claims a mound of innumerous skulls as all of her past victims that she's eaten, and Kasen reflects that even as just a severed arm she continued eating people. Ibaraki-Douji's Arm was also confirmed a tsundere in Touhou: Lost world.

Background Information: Ibaraki-Douji's Arm is, in fact, the formerly missing right arm of Kasen Ibaraki, sealed off from Kasen with the youkai blade Oni-Cutter after containing Kasen's malevolence. Reimu found the cursed box containing the arm near the shed of her shrine. After picking it up, she was transported to Hell, where the disembodied arm planned to attack and kill her.

Name background: Her namesake is derived from the legendary oni, Ibaraki-douji, one of the members of the Four Heavenly Kings. Kasen Ibaraki is, indeed, one in the same with Ibaraki-douji.

Design: This character looks almost exactly like Kasen, with nigh-identical clothes. Differences include her visible horns, her right arm being fully visible with a matching shackle and chain and the pressence of steel balls connected to both her legs with chains. She also seems to have more feral expressions compared to Kasen and shows bestial characteristics such as sharper-looking and slightly darker hair, slit pupils, long nails exclusively on her right hand and a noticeable fang when smirking, and transparent thigh highs. Of note is that her tabard and skirt is not magenta and green, but two shades of navy blue instead. Ibaraki-Douji's Arm is the same height as Kasen 6'1/186cm.

Story: In Chapter 47, Reimu fell into a death-like state as a result of picking up a box in or near her shrine's shed labeled "Oni's Arm". Picking up the box transpoted her to Hell. In Chapter 49 Part 1, Ibaraki-Douji's Arm revealed herself and began to attack Reimu, constantly taunting her with threats of death and of being eaten. In Part 2 of the chapter, the arm buried Reimu in an avalanche of skulls, intending to finish her off. However, she was then distracted by Kasen.

Kasen revealed that she deliberately placed her arm near the shrine so that Reimu could pick it up and get trapped in Hell. Her arm, delighted to see her, then accepted Kasen's proposal to reunite, create Kasen's true form. However, this was a front, as Kasen actually wished that her malevolence and her arm remain sealed away, going as far as hiding a fragment of the original Oni-Cutter blade in some dumpling wrappings given to Reimu so Reimu could do the deed. Upon realizing this, Ibaraki's Arm forcefully took control of Kasen's entire body to fight Reimu, but Reimu managed to successfully sever off and seal her again.

Kasen currently keeps the arm physically near by in mummified-arm form as a trophy of sorts as well as a reminder, comparing it to being able to see your own death close by.

Relationships:

Relationship with Kasen: Ibaraki-Douji's Arm is Kasen Ibaraki's severed right arm. She actually contains all of Kasen's malevolence, forced into Kasen's arm before the arm was cut off with a youkai blade. As revealed in Chapter 49 Part 2 of Wild and Horned Hermit, she appears to be in great terms with her. Kasen refers to her arm as her "partner" and uses the dignified pronoun "waga" for her. They both acted as if re-fusing was something they've wanted to do for a long time. However, this was a front, as Kasen actually wished that her malevolence and her arm remain sealed away. Upon realizing this, Ibaraki-Douji's Arm forcefully took control of Kasen's entire body before Reimu managed to cut off and seal her again. Kasen currently keeps the arm physically near by in mummified-arm form as a trophy of sorts as well as a reminder, comparing it to being able to see your own death close by.

Relationship with Reimu: Ibaraki-Douji's Arm seemed intent to kill and eat Reimu. Reimu, on the other hand, seemed intent to exterminate her, exclaiming that she hates oni. Things became significantly murkier when Kasen and her arm merged together. Hesitant to fight her former friend, Reimu initially couldn't bring herself to fight the arm at full strength. Upon realizing that Kasen herself was a distinct separate being from the arm and still on Reimu's side, however, she was able to fight with renewed determination and seal it off.

Extra information: Ibaraki-Douji's Arm is female just like Kasen. Ibaraki-Douji's Arm in this roleplay managed to escape her confines and made a physical body. Kasen's true form(who Ibaraki-Douji's Arm was formerly apart of}}), was in a group called 'Devas of the Mountain' or 'Big Four of the Mountain', consisting of Suika Ibuki, Yuugi Hoshiguma, Kasen Ibaraki(Who was in her true form at the time), and a unknown person(presumably a fellow Oni), it is unknown if Ibaraki-Douji's Arm respects her old oni comrades or not.