INVINCIBLE COURTESAN ON THE VERGE OF FORTY TAKES REVENGE ON HER HUSBAND'S KILLER

Haruka Takano is a 36 year old woman leading a peaceful and happy day life. But one day she sees the news about Tokyo IR, Japan's first casino, and becomes uneasy. She fears that her husband's gambling addiction might resurface. However, it's been 10 years since he's made a full recovery, and when she sees how kind and loving he is, she thinks that her anxiety is ridiculous. One morning however, Haruka notices that her husband's eyes are very vacant and hollow, so she calls out to him. He says he's fine. Then, after withdrawing all the deposits from their account, he disappears... (Source: MangaPlaza) — Description from AniList community (anilist.co).