I'm Useless Without You (2015)

I'm Useless Without You 2015 / 君がいなくちゃダメなんだ 2015 / I'm Nothing if there's no You , Kimi ga inakucha dame nanda

An Kanade is a picture book author. She's recently won an award for her work but has fallen into a creative slump. One day while searching for her cat, she comes across a mysterious message, left on a board in the city. She procedes to find more of these messages hinting at her father, a novelist who disappeared when she was just a child.