In English, most Japanese wrap-around clothing is referred to as a kimono. In this case however, this little baby/toddler coat would be appropriately called a yukata (浴衣).
The interesting part is that it has been made entirely from used cloth diapers. Back in the days, when Japan had not yet been such a throw-away society, the baby’s old diapers got recycled for a practical purpose. After a thourough cleaning, indigo dye was applied to give this lovely tie-dye pattern.
I had read about this technique in one of my Japanese textile history books and got very excited when I actually spotted one in an antique shop (the only tie-dye baby yukata I ever saw in three years of browsing antique shops in Japan).
The price, I believe, was 5000 yen in the early 90s, which equals about € 45 today.