HIMARI 日葵 is the everyday model, with a symmetrical five-layer construction and an approximate thickness of 10 cm. SORA 宙 is the 12 cm flagship, with a balanced medium feel that is slightly softer and fuller. Choose by intended use, preferred feel and available space rather than thickness alone.
For buyers researching shikibuton, shikifuton or a Japanese floor mattress, the key point is how this bedding is used: on a firm, ventilated surface, folded away when needed, and cared for as part of everyday Japanese living.