Satsujinki - Rank 2 in the House of X's leadership, a mutant with healing factor, slowed aging, and the ability to extend razor-sharp blades from her fingers, which are coated in a biological substance that makes them sharp and metallic. Also nicknamed Lady Deathstrike by Armor due to her blades. Named Yuriko Oyama, she is a perpetually teenage Mutant who was originally a student at Xavier's Institute for Higher Learning during 2010, who looked up to Wolverine immensely and Wolverine treasured as his most dutiful student, but when the House of X managed to find and attack the school's "evacuation base," a building in upper Toronto where the students were being kept for safekeeping during the war with the HOX, she was found by Higanbana, who by this point severely disliked her teacher due to how he always singled her out in combat due to her similarity to the Silver Samurai, and how manly and rough and insulting of the House and Cassandra he was. Higanbana offered to spare her in return for tortures and servitude as usual, and the terrified student accepted it, as unlike Wolverine, her mutation hadn't yet matured to the point she could heal from having her brain destroyed. In the aftermath of the attack, she was stolen away by Higanbana and went missing as a result, prompting for Wolverine to try and hunt after in hopes of rescuing her. Unfortunately, when Wolverine did meet her again at Genosha, she had been transformed by her experiences, and became practically a different person.

Before her encounter with Higanbana, she was an extremely upbeat, tomboyish girl with a deep admiration for Wolverine, having been her favorite superhero even back when she lived in Japan, far away from Wolverine's prowling grounds of the USA and Canada. She named herself Badger as her superhero codename, another mustelid that's vicious when angered, and wore an outfit heavily influenced by her mentor's. She loved fighting rough with her enemies, but was extremely averse to actually killing. Despite her high healing factor, she had low pain tolerance and hated getting hurt in any way, trying to avoid it if possible, leading to a dodging-heavy fight style. She had great relations with her fellow students, and her rough and tumble personality and sense of humor often lead her to alleviate their stress even when dealing with villain encounters. Likewise, she was very close to Wolverine, and while officially he was just one of her teachers, their relationship was at times closer to mentor and apprentice. Despite her overall rough attitude, she had a very fearful side, often fleeing when faced with an enemy which could kill her with ease, and it's what ultimately lead to her sad fate, as her fear of death when cornered by Higanbana left her to accept Higanbana's offer.

After being taken by Higanbana and resurfacing at Genosha, her personality has changed in horrifying fashion. Most of her liveli, hot-blooded energy has completely disappeared, and now she behaves in a composed and elegant fashion at all times, and her rough tone of voice has faded and been replaced with a much softer way of speaking with a very feminine intonation. She spends most of her time dead quiet instead of being loud, and her facial expression hardly ever changes from a serene smile and gaze. She is much more feminine than when she was with the X-Men, growing her hair out long, wearing skirts, and associating herself with feminine imagery such as butterflies and lilies like her second "mentor." She no longer fears death both due to the tortures she was exposed to by Higanbana and because her mutation has matured to the point she can survive attacks to the brain. She has complete pain tolerance due to the number of tortures she suffered, and even at times seems to relish being cut and hurt by her enemies, albeit since she hardly emotes much even during combat it's hard to tell. She has adopted her mentor's moral code, and offers the same chance at being spared to her enemies, complete with bizarre definitions of sins. She has no remaining friendship or feelings for any of her past friends like Angel and Elixir, and in particular considers Wolverine to be a sad old man who should just go and find some way to die already. The one thing that seems to remain is her love of fighting, since while she doesn't emote much at all during combat, Jean Grey and Kid Omega are able to sense she takes pleasure from fighting, due to a combination of thrill and sadistic joy.

By the modern day, she has become the leader of the Lilies, who she stands out among due to how her healing factor has meant she never bore any scars due to the torture Higanbana put her through, in contrast to the other, scar-covered Lilies, and acts as Sage's personal bodyguard. She is extremely loyal to Sage, protecting her with great ferocity, and tries her best to attend to her in other ways, such as making poetry for her, performing traditional dances for her, painting for her, and similar such things. However, Sage isn't really interested in these things - in fact, she never asked Yuriko to do it in general. She would prefer to protect Sage against any and all attackers, but respects Sage's wish to try and fight her enemies herself, and instead only ever intervenes when it becomes clear Sage will lose a fight. Due to not being a Psychic, she cannot take the name Psylocke or use the 10,000 winters technique, and has instead compensated by creating new techniques using her claws, as well as breaking her bones in strategic ways to enable moves she wouldn't be able to do with rigid bone structure. She is also prone to cutting her own limbs, or even her own head off when necessary to evade capture or death, and hides a specialized razor in her hairpin to serve that exact purpose whenever her hands are bound.

She feels somewhat insecure about her status as Higanbana's successor as the HOX's central bodyguard and leader of the Lilies, wishing that Higanbana would have survived Genosha or that Kanon lived up to her forebears and became the next Psylocke instead of running away as a child. As she still looks like a young girl even 10 years since her capture, she is prone to intentionally acting as a creepy teenager/child in order to frighten her opponents or throw them off their game, especially Wolverine. Despite considering Wolverine crude and worthy of death, she has no active desire to kill him, and finds his rage and anger with her and her master whenever they come face to face more annoying than anything, a loud distraction and nothing more. She's prone to quietly teasing enemies who get angry at her in combat, never losing her own sense of stoicism. Because of her backstory, she doesn't know what to do when left without the ability to contact Sage for orders, and pulls the petals from a metal flower ornament on her belt to make decisions, ala "loves me, loves me not."

She has good relations with most of the HOX, only really disliking Sebastian Shaw due to how he's more manly than the other members, and that's about it. She treats her Lilies with respect, having what appears to be a genuine friendship with all of them, but how willing she is to horribly torture them whenever they fail shows that it's mostly a farce. Her sadistic side often shows itself when she decides to create a new lily, and in particular wants to turn Armor into a lily because she reminds her of her younger self, and, being a telemorphic, could possibly learn to use 10,000 Winters. She feels shameful because she herself cannot use the technique, and thus cannot carry a "sword" like her master did.

In 2010, she wore a black and white hero costume influenced by Wolverine's, with bright red gloves with slits at the front for her claws to come out of, red boots with specialized traction, and a domino mask that curves to the sides like Wolverine's mask. In addition, it had stripes at the sides like Wolverine's costume, but they joined together to form an X design. At Genosha and in 2020, she wears a black uniform coat with golden buttons along the middle with black x designs, a collar to the coat styled after a pair of butterfly wings, and a pleated black skirt with red inner lining. On top of this coat she wore a black cape with white inner lining and rising spider lily patterns on the exterior. She also wears a red belt with a golden X design at the front, with a butterfly behind the X. Her shoes are black with golden, X-patterned laces, and go up to a little below her knees. In 2010, her hair is short and wild, while in 2020 it's long and silky, tied up in a ponytail with a dark metal butterfly hairclip with a blade hidden inside. Her cape is held up by an intricate knot styled after a spider lily flower. Her eyes are red with 3 pupils, which together are shaped like a Tomoe triskelion.