Himari no Mawari

is a japanese manga series written by Sakuragi Ren. It began serialisation in the January 2019 issue of Manga Time Kirara Forward.

The series was released under 3 volumes from June 2019 to August 2020.

Synopsis
Haruki Aizawa, 16 years old, 2nd year of high school, he likes to live efficiently. One summer vacation day, Himari Aizawa appears, calling him 'Onii-chan' and claiming that she's his little sister! As it turns out, Haruki's father recently remarried, and his new wife brought a daughter with her. However, since both of their parents are overseas, it'll only be the two of them living under the same roof. And for some reason, Himari seems very obstinate about spending as much time with Haruki as she can!

(Source: MU)