Gorou has a crush on his older stepsister Haru. Unfortunately for Gorou, Haru happens to love teasing him sadistically in every way possible.
A 4-koma comedy about their wacky day to day life and interactions.

Hoozuki-san Chi no Aneki - Nano Shucchouban and 2 chapters of Hoozuki-san Chi no Aneki - Nano Branch are included in volume 3.

Volume 1:
1-3. Lost After School
4-6. Rain Festival
7. Blue Imaginary Birds
8-9. Walking with a Friend

Contains eight stories titled: Girlfriend in the Sky, Ankoku-san, Kami-sama Make-Believe, Downtown Train, Harumage, Ekstasis, Ao and After School Show. Each story possess different characters, but the these of love and its different forms of expression is present throughout.

The 4-koma crack comedy is back, and this time around Gorou's crush on his sadistic, older stepsister Haru has reached the stage where more or less openly sexual innuendos have become part of their everyday life.
The pair's "peaceful" days would have continued if only it weren't for Haru's cousin Aoi-chan and (dangerously?) younger sister-like existence.