Nishikawa Futon Haramaki (Stomach Warmer) Just attach it to your existing futon! For those who find their current futon isn't warm enough, but don't want to buy a new one or add bulky bedding. We highly recommend this product. You can easily attach this "haramaki" (stomach warmer) to the parts of your futon you want to warm. Made with moisture-absorbing and heat-generating material, it warms your cold feet, stomach, and shoulders.