What is the fine-grained topic of the following text: Ikeda and Shibata have teamed up to make this range of knives, Ikeda hammers out the knives and Shibata sharpens and finishes the knives in his work shop in Fukuyama city, Hiroshima, Japan. Only return the topic.
Ikeda and Shibata's collaboration in making knives in Fukuyama city, Hiroshima, Japan.