summer bedding; summer futon
Refers to lightweight futons or bedding specifically designed for hot summer nights, often made of cooler materials.
It's getting hot, so I switched from my winter futon to my summer futon.
This summer bedding is breathable and comfortable even on sweltering nights.
General term for Japanese-style bedding; 夏布団 is a seasonal variant.
Compound of 夏 (natsu, 'summer') and 布団 (futon, 'bedding').