This is a gauze cotton 100% sleeper from Sandesica. The website says it's for ages 3-7, but my child outgrew it at 100cm. I think it's best suited for 2-3 year olds who are around size 100. It becomes fluffy after washing, and because it's gauze, it's perfect for children who tend to get hot. I bought it on Amazon for around 3,000 yen. It's a good sleeper for spring to autumn.