Chikan to nozoki: Neesan no shinshitsu

Directed by Sakae Nitta

With Akane Koizumi, Mika Tamaki, Yuuna Hide, Hajime Ishigami and Masahiro Yoshida

Yumiko, a classmate of Tadashi who just married his brother, lives under the same roof without knowing Tadashi's feelings, and they have a fierce nighttime affair. Of course, Tadashi is aroused by the two of them, and he doesn't understand either. One day, her husband, her brother, finds a letter addressed to Yumiko from a woman who adores her husband...