The Mystery of the Ultimatum Game, by Kayoko Kobayashi,

 I get very little snail mail these days, but every now and then an interesting book arrives.  The latest is the English translation of the prizewinning book (originally in Japanese) by Kayoko Kobayashi, an economist at Nanzan University. (The link is to her English language webpage, but Google translate is still helpful...)

 The Mystery of the Ultimatum Game. Why We Are Predictably Irrational by Kayoko Kobayashi, Springer, 2025.

"The original Japanese edition won the Nikkei Prize for Economics Books (the 64th Nikkei-Keizai Tosho Bunka award) in 2021, an accolade bestowed upon an outstanding economics book published in a given year. Furthermore, this edition also received the Takashima Kunio Jiyu Prize Encouragement Award in 2024."

While the book invites one to think about "irrationality," the introductory chapter ends with a brief encomium towards the traditional notion of economic rationality, as exhibited by those mythical creatures, homo economicus, also known as the Econ.

"I will close with a modest defense of the Econ.  I said earlier that the Econ might not be much fun to be around. Yet the Econ is also a good person, and in some sense an amazing one.  The Econ does not get jealous. The Econ does not deprecate himself in comparison with others. He does not abandon hope for the future nor sink into despair. He is the kind of person who, no matter how hopeless the situation may seem, doe not dwell on the past but calmly assess the present, focuses solely on the future, and pursues what needs to be done with unwavering determination, choosing the best course of action from the options available."