Butter by Asako Yuzuki

https://www.goodreads.com/book/show/200776812-butter

The cult Japanese bestseller about a female gourmet cook and serial killer and the journalist intent on cracking her case, inspired by a true story.

There are two things that I can simply not tolerate: feminists and margarine.

Gourmet cook Manako Kajii sits in Tokyo Detention Center convicted of the serial murders of lonely businessmen, who she is said to have seduced with her delicious home cooking. The case has captured the nation’s imagination but Kajii refuses to speak with the press, entertaining no visitors. That is, until journalist Rika Machida writes a letter asking for her recipe for beef stew and Kajii can’t resist writing back.

Rika, the only woman in her news office, works late each night, rarely cooking more than ramen. As the visits unfold between her and the steely Kajii, they are closer to a masterclass in food than journalistic research. Rika hopes this gastronomic exchange will help her soften Kajii but it seems that she might be the one changing. With each meal she eats, something is awakening in her body, might she and Kaji have more in common than she once thought?

Inspired by the real case of the convicted con woman and serial killer, "The Konkatsu Killer," Asako Yuzuki’s Butter is a vivid, unsettling exploration of misogyny, obsession, romance and the transgressive pleasures of food in Japan.