I Found a Kitten

Atsuki Komiya is a college student who's living alone. Suddenly his sister visits and asks for a favor, which is to take care of his niece Kasane for two weeks. A story about the awkward relationship of these two, the confused Atsuki and the sullen Kasane, living together. Which direction will this story go…? (Source: Bookwalker, translated) *Note: Chapter count includes 2 extras*