This is a Fukuro obi
with luxurious butterfly and 'Karabana' (imaginary flower in china) and circles pattern, which is woven.
Foil threads included in fabric and the pattern twinkle gently.
Textile is silk, and it has soft to the touch.
Sangs on Otaiko pattern may show when tied, but they are not noticeable.
It has some other flaws, such as folding lines, as shown on photos.
Please see photos for details.
Overall, it is in very good condition and can continue to be worn!