It is revealed that Karen sought out Kaiki on her own to stop him, but he poisoned her during their encounter.

Watch the episode to see Koyomi's race against time to save Karen from her supernatural fever: Nisemonogatari Karen Bee, Part 4 - Watch on Crunchyroll Crunchyroll• Jan 28, 2012 Nisemonogatari Episode 04: Karen Bee, Part 4

To calm his frustration, Koyomi takes a bath, where he is joined by Shinobu Oshino , who emerges from his shadow. This scene is significant for their relationship, as they begin to reconcile and bond after the events of Kizumonogatari while discussing the nature of Karen's supernatural ailment. Thematic Context

The episode picks up after Karen has been afflicted by a supernatural "Wreathe-Fire Bee" oddity.