Elder Sister's Diary by Hiroyuki Nasu

3.33

Hayashi Taro is still a high school student, but lives in Tokyo with Yuko, who works at a no-pan coffee shop. Shigeya Yoshida, an architectural designer in Yokohama, likes June and goes to hotels. Yoshida's wife, Hideyo, notices the existence of June and is very jealous. In addition, Hideyo had a younger brother named Kiyoshi, who had feelings similar to love for his sister. When June and Shigeya were dating Shonan at night, Hayashi Taro attacked Shigeya....