Karen Bee, Part Six Episode 6

Koyomi only managed to drain half of the poison in Karen's body, and although she was not completely healed, her fever has become slightly diminished. On his way to Hitagi's house, Koyomi stumbles on Mayoi again and confides to her about his sister's situation. Upon arriving at Hitagi's house he finds out that Hitagi managed to arrange a meeting with Kaiki and is preparing herself to enact revenge on him. Koyomi explains to her about Kaiki's encounter with Karen and convinces her to not confront him without his help. Back at home, Koyomi learns from Tsukihi that Karen is missing, and worried that she might had left to face Kaiki once more, he asks Shinobu's help to find her.