"Whim…!!" (気まぐれ…!!, Kimagure…!!, Viz: On a Whim…!!) is chapter 307 of the original Naruto manga.
Sasuke asks where Kakashi is, so Yamato explains that he is Kakashi's stand-in. Sasuke concludes that Sai is therefore his own stand-in, and repeats Sai's claim that he wants to restore the bond between himself and Naruto. He laughs at the idea, but Team 7 realises they were wrong to doubt Sai and accept his help with bringing Sasuke back to Konoha. Sasuke has no interest in returning, so suggests killing Naruto to make things easier.