You need them to register a birth certificate, to marry, to open a bank account and even to receive a parcel. You might say the hanko validates every official occasion in Japan.

Hanko, or seals, were formally introduced to Japan in the 8th century, in imitation of the established Chinese practice. With the rise of Zen Buddhism around the 12th century, the practice of using hanko was common among monks returning from China. As powerful daimyo began setting their personal seals to official documents issued within their domains, the use of seals became a national custom.

Before the Meiji Restoration, the use of seals was limited to the upper class. That changed drastically in 1887, however, with the establishment of a nationwide system for the registration of private seals, which made the seals a requirement. Today, registered seals are used to validate legal contracts and other official documents.

Although some consider the practice of using hanko bothersome, Mutsuko Ito's craft would go a long way to change that perspective.

Instead of expensive ivory or ebony, Ito uses natural wood for the hanko she creates. In addition to calligraphic characters, she engraves animals and flowers on the seal's face which give her creations a feeling of fun and warmth.

Born the older of two daughters to a hanko artisan, Ito said jokingly, she was "brainwashed to succeed her father in the family business," and started engraving hanko after graduating from high school.

Her father died soon after, however, and Ito was forced to teach herself. She explored her own style and taste, but kept the techniques and tools her father left her. Though many hanko artisans mechanized the engraving process, Ito stuck to the traditional hand-engraving.

About 10 years ago, Ito learned that artisans used tea tree wood to make seals in the past, which inspired her to start using the dead wood she collected in forests and on mountains to make her creations.

In 1997, while trying to think of something new to make, she decided to engrave rabbits, the Chinese zodiac sign for 1998, onto her hanko. When she sold the illustrated seals at department store events, the novelty items instantly appealed to etegami (postcard painting) lovers, who were in the market for a unique stamp on their art. "I was flooded by orders after my hanko appeared in a magazine article," the 54-year-old artisan recalls, "and I had to work frantically to fill them."

Now her seals come in a variety of materials and patterns, and appeal to a much wider audience.

The natural wood Ito uses ranges from bamboo, tea tree and Japanese plum tree to cherry tree branches, camellia tree and Japanese cypress root. Her husband, who helps her on his days off from his regular job, collects the raw materials in the mountains every November and stores the wood for three to five years until it is thoroughly dry. Later, the branches are cut into certain lengths and some are peeled to make their surface smooth, while others are lacquered to make them lustrous.

"Because I use sectioned pieces of natural branches, the seals vary in size and shape," Ito said. "All seals are different, and each customer has an original."

Characters and patterns are chosen to meet the customer's preference and the occasions for which the hanko would be used. The most popular designs are illustrations set beside the customer's name. Following the natural curves of each branch, Ito engraves things like a swimming dolphin, the back of a sitting dog, or two rabbits looking at the moon. Her repertoir of illustrations grows as customers make unique orders.

Clients are welcome to observe the hanko-making process as Ito sets a branch piece into a vice, draws a design with a fine brush and engraves it with her well-used chisels. Often, the artisan chats with her waiting customers during the one hour that it takes her to create an original seal.

"Customers actually became a good correspondents just because they want to use the seal I've created for them," Ito said. "It's really nice to have a seal that is fun to stamp."