Himari no Mawari
ひまりのまわり
A 16-year-old high school student named Haruki Aizawa enjoys living efficiently. During summer vacation, a girl named Aizawa Himari appears, addressing him as "Onii-chan" and claiming to be his younger sister. It is revealed that Haruki's father has recently remarried, and his new wife has a daughter. With both of their parents away, Haruki and Himari are left to live together. Himari insists on spending a significant amount of time with Haruki.