Though the Japanese live longer than anyone, they pray for even more longevity—for humans and deities alike. These four auspicious kanji are associated with longevity, which is a natural fit for 亀 and 鶴; as one proverb has it, turtles and cranes live thousands of years. Meanwhile, 寿 means "lifespan" and "longevity" in words for those concepts and appears in many terms for milestone birthdays. Finally, because the pine represents long life, thanks to its evergreen needles, images of that tree abound at weddings and on New Year's cards. Similarly, twin pines symbolize a long, happy marriage.

Metalworking may not seem relevant to daily life, but these kanji are. Two combine in 鍛錬, enabling people to express desires for toned bodies, sharper minds, and self-discipline. After all, the Japanese relentlessly push to improve themselves and others—hence the exactitude of sushi chefs who rigorously train employees. The bundled characters also shed light on history, from the ancient need for metal (including in mirrors for sacred Shinto rites) to the 1941 mandate to melt down metals, even temple bells. These kanji have even inspired figurative language, as with a term for "forcing into a mold."