Mamoru really is a national treasure.
And i don't agree that their dad is irresponsible, sounds like his friend was projecting that on him. He's the reason they're able to live as neets without having to worry about whether they'll have food on the table the next day or a roof to live under, and he goes to work every day religiously to support his family. Adding to that he's neither abusive nor overbearing, and is capable of showing heartfelt appreciation for the smaller and bigger things his kids do for him and their family, from the day Mamoru saved his sister from being stung by bees to the shoulder massage tickets he gets from them at his birthday (ch209). He's as good of a dad as they, especially Haruko, could've ever hoped for.