Birds Without Names

Towako still can't forget Kurosaki, even though they broke up 8 years ago. She now lives with a man named Jinji. Jinji is 15 years older than her. Towako hates Jinji who is poor and vulgar, but she lives with him because of his wage.
One day, she meets Mizushima who has a wife and kid. He reminds her of Kurosaki. Soon, she has an affair with Mizushima. A detective visits Towako and tells her that Kurosaki is missing.
(Source: AsianWiki)
~~ Adapted from the novel "Birds Without Names" (彼女がその名を知らない鳥たち) by Numata Mahokaru (沼田まほかる).