Shiki Futon (Futon Mattress) at the time of delivery is very fluffy and voluminous, measuring over 4” (10 cm) in the thickest center position but after about one week of usage the fluffiness will begin to settle,
and the mattress will transform into a stiffer, denser futon. After about two to three months of use, the cotton padding becomes even thinner (more constricted) and the futon will become about half of its original thickness.
Although the volume decreases, the cotton fibers "support features" become activated and the futon becomes a mattress that will support your proper sleeping posture.

How to care (a new window of pdf file will open)
Do Not wash
Air out under the sun