Happi Coat Happi is a traditional Japanese straight-sleeved coat usually made of indigo or brown cotton and imprinted with a distinctive mon (crest). Originally, these represented the crest of a family or organizations. This modernized Happi Coat is made of Satin like materials accompany by beautiful ancient cerography of Good Fortune, Great Career Advancement, Longevity, and Enjoy. It feels great on your skin, a perfect sleepwear.