We don't know what caused it to die after it started to leaf again in spring. The soil wasn't water logged. It was moist but not soaked. We didn't notice any apparent signs of disease or pest infestation. I have read that some varieties of dwarf Japanese maples are difficult to grow in containers compared with others. I did not find specific information on Beni Hime.
TH is especially saddened by the loss of the beni hime. It was a cute dwarf Japanese maple. Anyways, we'll give it some time before we acquire another.