I'm looking for suggestions for manga series where the main characters are an adult woman who is childish / careless / forgetful, and a young boy who is mature for his age and often seems like he has to look after the woman. The woman is the boy's main caregiver, but not necessarily his mother or a blood relative (preferrably not). The manga should focus on the relationship between the two of them, but I'd like something lighthearted rather than anything too full of drama.
I've read a few which I love where men are looking after little girls (Yotsuba&!, Usagi Drop, Aishiteruze Baby), but I want something a little different, that isn't just a generic story about a mother and son. >3<
I really hope there's a manga like this, please help!
EDIT: Please DON'T recommend romances! I'm NOT asking for older woman / younger man romantic relationships, I'm looking for familial relationships.