Kasane Kujiragi

Kujiraki Kasane (鯨木重) is a character in the Durarara!! light novel and a wielder of Saika.

Although mentioned in passing in previous volumes, she first appears in person in Volume 10 as Yodogiri Jinnai's secretary, and is described to be a young woman wearing a western suit. She is shown to wear spectacles in illustrations. She is described to be calm and quiet.

Kadota's Coma Arc
Kujiraki shows up first with Yodogiri when dealing with Shijima's family.

She then appears with Yagiri Seitarou to kidnap his niece, Namie. Kujiraki incapacitates Namie by electricuting her with an electric glove, which Namie remembers Izaya buying before for fun. Namie fights until they tell her they have her brother Seiji, at which point she makes interesting and terrifying threats to be carried out if they touch a hair on his head.

She makes a major appearance in the second half, where Orihara Izaya arranges for Niekawa Haruna's "children" to kill "Yodogiri Jinnai" by driving them over. It is at this point that Yodogiri Jinnai is actually the name of a group as opposed to one man. When the Yodogiri ("Number Eight") beside her is injured, Kujiraki does not respond but proceeds to calmly call another Yodogiri ("Number Five"), with a similar voice, to replace him, only to hear him get knocked down as well over the phone. Izaya calls her, and confronts her as the leader of the organization "Yodogiri Jinnai". At this point, he is being guarded by Slon.

In the conversation, Izaya claims to have had no proof, only guessing based on his own research. On questioning, Kujiraki reveals that although "Kujiraki" is not her real name, the name was given willingly, and the original Kujiraki has likely started a new life in Southeast Asia. The men acting as "Yodogiri Jinnai" are said to have partaken willingly in the prior immoral actions in their own interest. Izaya says that Yodogiri Jinnai has been active since about twenty years ago, and asks about her age despite her young appearances. She claims to have no obligation to answer, evading the question.

Izaya confronts her about spreading rumors in Dollars about Dragon Zombie (/Dead Dragon?), Izaya's gang, having been the culprits behind Kadota's accident. He recognizes her impersonation of Kanra in the online chatroom as a warning, and asks why she added "nya" behind her sentences. Kujiraki says that it's cute. Izaya is incredulous and asks if she wears cat ears and a tail in front of the mirror to pose and say "nya" on her days off. After silence, she says it sounds alright and she will try.

Izaya mocks her with the irony that Saika, which she sold to Kishitani Shingen, has become her enemy. (Niekawa Haruna's Saika's children attacked Yodogiri Jinnai.) He skypes to Niekawa Haruna with instructions to have Kujiraki kidnapped.

Kujiraki says that Izaya and Heiwajima Shizuo are obstacles for her motive of "bringing in goods", and reveals that she is aware that Izaya had Shizuo arrested. She proceeds to say that the "children" cannot focus with someone like Shizuo on the streets, although Niekawa Haruna's "children" appear to have given up. She reveals that she was the owner of Saika twenty years ago. Izaya asks if being a previous owner has granted her some privelege, to which she replies that other than cutting, there is another method to increase Saika's children that the current wielders are likely unaware of. She calls this technique branching - to break Saika's original form, and use the shard to smelt another blade.

Izaya turns around, alarmed, only to be grabbed by the throat by Slon and smashed into concrete. Kujiraki asks for Izaya to be taken to an office so she can question him regarding Celty's head.

After this, as she talks to herself, Kujiraki thanks Izaya for dealing with Yodogiri Jinnai and "freeing" her  from her monotonous everyday life. She says Izaya in indeed an obstacle in Ikebukuro, third after the Awakusu organization and Tsukumoya Shinichi.

Saving Izaya/ Haruna is back Arc
Tsukumoya Shinichi comments on Kujiraki in a blog post. It is revealed that Kujiraki is a halfbreed, explaining her youthful appearance. It is also revealed that Kujiraki shares the same non-human mother as Hijiribe Ruri's mother, although their fathers are a generation apart, resulting in Hijiribe Ruri being Kujiraki's niece, with an age gap of about twenty years. Kujiraki was sold to Yodogiri Jinnai, by her mother (Ruri's grandmother) shortly after her birth, about right after Ruri's grandmother ran out on the family. Having grown up under Yodogiri Jinnai's shadow, she continued using his name after he passed away. Tsukumoya Shinichi compares her to Orihara Izaya, saying that if Orihara Izaya is naturally evil, Kujiraki is a human made by humans, and thus a perpetrator as well as a victim. Having grown up in such a setting, Kujiraki's fate was mapped out from the start, and the only path of living for her now is the underground practice.

Being that Hijiribe Ruri, despite having the same non-human blood, has managed to chase her own dreams and happiness, it is mentioned that Kujiraki does feel somewhat envious, but not to the point of hatred. For example, when Hijiribe met misfortune, it is said that Kujiraki did not feel satisfaction from it.

Supposedly, the Saika "branching" Kujiraki spoke of was when she sold Saika to Kishitani Shingen. This means that two Saika blades already existed twenty years ago. Of these two, one is still in the possession of Kujiraki, whereas the other is with Sonohara Anri.