Well, I forgot the title of the manga but....

I remember that the storyline was that a man adopted a white haired child his grandfather had with a mangaka after none of his relatives did not want to adopt her. I think her name was Rin or something, kind of fuzzy to remember. Anyway, the first half of the manga was about her childhood, and how the man had to take a lower paying job in order to have time to care for her. Also, he planted an age measurement tree for her just like his family did with him. The white haired child also had a friend she made in kindergarden....his name starts with a D or something.

The second half of the manga is about her high school life, and mostly about the interactions between herself and her childhood friend.

Does anyone know this manga? I can provide more information!

It's Usagi Drop

Agreed!! You remembered quite a lot of the details, tarika.