Yui, a widow who lost her husband in an accident soon after getting married, is forced to live with her stepchild, Shota. While supporting his heartbroken mother-in-law, Shota is unable to suppress the lust that wells up within him as Yui comforts herself in front of the deceased's portrait late at night, and he forces himself on her... Yui, feeling lonely, also accepts his desire, and the two begin their twisted married life together. However, this life is not going to go well, and it comes to an abrupt end. One day, Shota finds a letter that Yui has written to his father on his father's Buddhist altar. The contents of the letter are...