HIGASHIOSAKA, Osaka -- From rocks to starfish and other organisms, Tajiri Thin Section Lab here has gained attention for its expertise in cutting materials into ultrathin slices, known as "thin sections," polished to a thickness of just 0.02-0.03 millimeters. This exceptional artisanship has earned it a spot at the Expo 2025 Osaka, Kansai.

The mastermind behind this work is 67-year-old Rie Tanaka, who goes by the professional surname Tajiri. Thin sections are primarily used in geology, where materials like rocks are ground down to a level so thin that light can pass through them, enabling detailed examination under a microscope.

The process begins by cutting rock samples into cubes about the size of an eraser using an electric cutter. These samples are then mounted onto glass slides measuring 28 millimeters by 48 millimeters. Using a disk-shaped grinding machine, the samples are gradually polished, and the final touches are completed by hand with polishing powder. Currently, there are only a few dozen thin-section specialists in Japan.

Tajiri's passion for stones began in childhood, leading her to study geology at university. After graduation, she joined the National Museum of Nature and Science in Tokyo as a part-time staff member, where she honed her thin-section skills. Although she left the field temporarily to focus on having children, her love for thin-section work never faded. She later returned to the craft, refining her skills further at universities and other institutions.

In 2010, Tajiri pushed the boundaries of thin-section technology by developing a method to solidify biological tissues for polishing. By replacing the water within the tissues with resin, she made it possible to grind and polish them directly -- opening up new possibilities beyond geology.

In 2016, Tajiri returned to Higashiosaka to care for her aging parents and set up the Tajiri Thin Section Lab in her home garage. As one of the few specialists in Japan capable of creating thin sections of biological tissues, she collaborated with researchers to produce thin sections of urinary tract stones and human teeth, making significant contributions to medical research.

Her expertise now extends to industrial materials, including carbon fiber and concrete, where her thin sections provide valuable insights for research. Looking ahead, Tajiri is eager to pass her skills on to younger generations.

"I want more people, including the public, to take an interest in thin-section technology," she says.

Tajiri's work will be on display at the Osaka Healthcare Pavilion during the Osaka Expo from July 8 to 14.

(Japanese original by Tsutomu Koseki, Osaka Photo and Video Department)