OOZ662 said: "Life of Maid" is the main storyline. "Life of Maid-chan" is a bit of a sidestory, or perhaps a self-parody, wherein the ages have been swapped.
Oh hey, this is Life of Maid-chan. Now I feel stupid.
I'm surprised no one's commented on the irony of this, seeing as Youmu had a wetdream of what Yuyuko would look like as an adult early on in the comic and now that it's happened Youmu is too Chibi herself to appreciate it. XD