Ok, ever since I started reading this manga, i've been asking myself, what does the title mean? Anyone know? At first i thought her name was Nanaco, or Robin, but it's neither, so if anyone can enlightened me, i'd appreciate it.

From my inaccurate perspective is Konatsu (male lead) being the 'seventh robin' or 'seventh child'.

As you know 'nana', in Nanako, means seven.
Nako is the second oldest of five children, with the addition of Konatsu's older brother and himself after his brother married Nako's sister. Therefore, seven robins in a nest, the nest being the Yoshino family home. And Konatsu, or maybe Nako, is the seventh robin.

Don't ask how I got this. But that's what I think.
Who knows, maybe the title doesn't have a general meaning?
o__o