Black Widow Business (2016)

Kozo Nakase attends meetings for single widowers looking to remarry. He meets Sayoko Takeuchi and eventually marries her. Not longer after their marriage, Kozo Nakase suddenly collapses and dies. Kozo Nakase leaves everything to Sayako. The rest of his family are left out of his will including his daughter Tomomi. Tomomi hires a private investigator, Honda, to find out more about Sayoko.