Ijintachi to no Natsu

Harada is a successful scenario writer, who broke up with his wife and children and lives alone in an apartment. While indulging in melancholy, mainly on his failure as a husband and father, he meets and befriends a couple with a strong resemblance to his late parents and a mysterious woman who offers her company and
become lovers. As much as he likes both these encounters, he suddenly realises that his body becomes weakened and face is becoming zombie-like. Adapted from a novel written by Yamada Taichi.