The UNPRLD Seiji is the signature yoyo of Junsang Park.

The Seiji is based on the Cognition series. The yoyo is larger and wider than the cognition shape, and has a large winged rims. UNPRLD went through 5 prototypes to come up with this final design. The result is an extremely stable playing yoyo that is easy to control, push, and rely on for front, side, and horizontal styles.

The name Seiji is the Korean pronunciation for the sage flower. These low growing, evergreens have long stood for various qualities like long life, thoughtfulness, good health, and wisdom in the language of flowers.

The flower language of sage is the core of Junsang's philosophy of life. Junsang, for the past several years, has lived a very disciplined life for his well being mentally and physically for yoyo. His passion for knowledge, health, and the ability to not be hindered by the modern phenomenon of demoralization is what made him choose this name.