I love this story, and I especially love the way Hiro-chan was written and drawn. The drawing is realistic, he really looks like a baby. Plus the way he behaves is in line with how a child would behave at 3-5 years old. No exaggerated intelligence and wisdom. And don't get me wrong, there are children who are very intelligent and wise for their age, but there are stories where they seem to exaggerate their personality a lot, and the character seems like just another adult in a child's body.
Boku no Papa to Papa no Hanashi