Gunze and Kao launched SmaShee, a jointly developed brand for men's light urinary leakage, on September 7, 2026. Gunze's boxer briefs have an internal pocket for Kao's separately supplied absorbent sheet, released the same day. The companies developed the combination for men who hesitate to use specialist products because of their appearance or the inconvenience of changing and carrying inserts.
Gunze describes a three-layer front: mesh next to the skin directs moisture to the sheet, a middle layer helps limit transfer to outer clothing, and an outer layer matches the rest of the briefs. The dedicated sheet is specified at 20 ml absorbency and 3 mm thickness. The pocket is designed to keep it in place during movement, while cut-off fabric reduces bulky seams.
The boxer briefs launched exclusively on Amazon in Japan, priced at ¥2,860 including tax, in M, L and LL sizes and black, red or navy blue. Gunze instructs users to insert the sheet with its white surface facing the skin and remove the used sheet before washing the briefs.