I remember reading parts of this manga a couple of years ago. The guy was a writer. The girl was really young and somehow she makes it into the guys yard (I think she sunk in because she was chasing a cat?) She's really depressed for some reason and she doesn't show emotion a lot. The guy's publisher sees the girl and convinces the writer guy to write a story about her (really creepy imo). The little girl has a crush on the writer.

I also remember there being two other little kids that end up hanging around the writer's house too. A boy that has a crush on the girl and another little girl that was really mean to the main girl at first.

That's all I can remember.

Thanks in advance to whoever knows what this manga's title is.

Kore wa Koi no Hanashi

If you want more there's another very similar manga, Hana no Namae.

That was it! Thanks