At the end of the Karakura arc:
Kubo: "I have a great idea for a plot in this next arc. We'll reveal at the end that it was actually the nice dead guy who was behind everything, and that he's now the main villain."
Editor: "BRILLIANT! Then what?"
Kubo: "Dunno, we'll figure that out later."
Editor: "Works for me."
Two years later, just as Soul Society is reaching its end:
Editor: "Say, did you ever figure out where you were going with the plot after this?"
Editor: "You didn't? ...Ah well, whatever. You're popular enough with the kiddies now, you don't really need my help. From now on, just whip a script up over the weekend, e-mail it to me, and I'll rubber stamp it for the presses."
...And that's why Bleach now has tentacle rape themed villains.