The tapered shape of the Naka-ai provides an elegant surface for the painstaking Chinkin engraving work involved in the creation of the Housoge Kikyo Platinum. Silver powder is carefully applied to the engraved lines, set against a dark blue Kikyo Urushi background. It is then sealed in place with a final layers of clear urushi lacquer in a time honored tradition.

Designed by Nakaya master pen designer Shinichi Yoshida in collaboration with Classic Fountain Pen's John Mottishaw, the Naka-ai model of pen, with its peaked ends and tapered body, combines many of Nakaya’s most distinctive design features in a single model. "Naka-ai" has the meaning of middle or in-between, and brings to mind the Middle Way of Buddhist practice with its emphasis on balance, integrity, and centeredness. Appropriately enough, the Naka-ai occupies a midway position between Nakaya's smaller Piccolo series pens and the longer desk pen.

Nakaya pens can be filled with bottled fountain pen ink using the provided converter, and can also use Platinum brand cartridges. Hand-painted Maki-e converters are also available.