This is a Fukuro obi
with auspicious 'shou-chiku-bai'( pine tree, bamboo and ume blossom) and crane in Hishi (diamond shape) lattice pattern, which is woven.
Foil threads included in fabric and the pattern twinkles gently.
Textile is silk, and it has soft touch.
Actual color is in black, not as blueish seen on photos.
Snag on Otaiko pattern will not know when tied.
It has some other flaws, such as a folding line, as shown on photos.
Please see photos for details.
Overall, it is in very good condition and can continue to be worn!