I read the manga, it's rather nice story..till chapter 20 I think.
Suddenly the guy who was plain and simply average became some kind of store superman out of nowhere - if he was that hardworking then it was obvious that he had some skills but I think that improvment of his character was too sudden and make it less believable.
I also can't appreciate the plot device called "Daughter who needs to seduce some manager" - maybe I don't understand Japanese culture, but that does look a bit unbelievable too - their previous problems were rather realistic, now it just looks like new problems appear that odds of happening are quite slim.
Our main hero and heroine seems to be very childish in this relationship - I would bet my money they know next to nothing about each other, hence all that dirt keeps coming out. Because it's impossible to sit down and discuss things, to come up with plan - everything from them requires a lot of emotions and unnecessary moves. They can't decide together on catching the culprit, they can't tell each other about their life problems and they can't properly split duties in the house - that thing I can't understand and somehow it irritates me - although it is that disorganised lifestyle they have which makes us smile and is cause of their problems.