Nankuru Nee-san

The manga follows Issa Kinishi, a young man who worries and concerns himself too much over many different things, and spends his life being harmless and inoffensive. One day he meets a beautiful, tanned enigmatic young woman. This young woman uses a smartphone with a cracked screen, goes into restaurants without caring about their online ratings, and makes curry without caring about the stains she gets on her clothes. She weighs on Issa's mind so much that he accidentally starts stalking her.

(Source: Anime News Network)