Saika gerät allmählich außer Kontrolle, doch als seine Mutter auf den Plan tritt, beruhigt sich die Situation wieder. Mit Anris anschließendem Krankenhausaufenthalt kommt allerdings ein Stein ins Rollen, der den Alltag der drei Oberschüler wahrscheinlich etwas aufrütteln wird.
Sonohara pokes Niekawa with Saika, and shows her a flashback of how she became its wielder. Sonohara's father was an antiquities dealer, and constantly beat up her and her family. Her mother then got possessed by Saika, killed her father, and committed suicide. Sonohara then grabs the cursed blade, and becomes its wielder. Meanwhile, Shizuo beats up Niekawa's "Saika children," flashing back to his past. Sonohara then assimilates Niekawa's Saika, and as a result takes control of all of the Saikas in Ikebukuro. Sonohara apologizes to Celty for attacking her back in Episode 5. Mikado later visits Sonohara at the hospital, and after realizing she has met the "unusual people," warns her to stay away from the non-normal. As a result of Niekawa's assimilation, Sonohara has gained her and all of the Saika's memories; she suspects that Izaya is up to something. Mikado is later shown contacting members of the Dollars, but it is unknown for what reason. The episode concludes, as Izaya's plot deepens further; he is revealed to be behind several events in the slasher arc. He has caused a split of the city's population into different "factions;" Saika/Sonohara's army, the Yellow Scarves, and the Dollars; and knows that they will fight amongst each other. Kida, not knowing Anri Sonohara's true nature, retakes his place as the leader of the Yellow Scarves. He suspects the Dollars to be responsible for Sonohara's injuries, and vows revenge.
Anri ferisce Niekawa con la vera Saika mostrandole i ricordi di come ne è diventata la portatrice. Assimila la Saika che possedeva Niekawa controllando così anche tutte le altre che erano comparse a Ikebukuro. Come risultato Anri ha acquisito anche tutti i ricordi di Niekawa convincendosi che Isaya gioca qualche ruolo in tutta questa faccenda. Infatti si scopre che ha a cha fare con diversi avvnimenti riguardanti il Laceratore e che è opera sua la suddivisione della popolazione in fazioni contrapposte: le Saika, i Turbanti Gialli e i Dollars. Intanto Kida, non conoscendo la vera identità di Anri, riprende il proprio posto a capo dei Turbanti Gialli, scatenando una rappresaglia contro i Dollars.
偶然現れた那須島を追いかけ姿を消す贄川春奈。そしてその後を追う杏里。罪歌を操り、斬り裂き魔の集団を統率する春奈との対峙によって、杏里の過去が徐々に明かされていく。
時を同じくして、南池袋公園で斬り裂き魔と闘争を繰り広げ続ける静雄。
倒しても倒しても向かってくる斬り裂き魔達。それを迎え撃つ静雄の顔には、嬉々とした表情すら浮かんでいた。
Haruka Niekawa se va para perseguir a Nasujima, quien aparece casualmente en su casa. Anri decide seguirla y mientras se enfrenta a Haruna, se revelan datos de su pasado. Mientras tanto, Shizuo pelea contra un grupo de apuñaladores en un parque de Ikebukuro.
