noun
thin under-belt for kimono
A narrow, soft belt worn over the kimono and under the obi to keep the kimono smooth and protect the fabric.
着物を着るときは、まず伊達締めを締めてから帯を結びます。
When wearing a kimono, first tie the datejime, then tie the obi.
The term 伊達 (date) refers to stylishness or dandyism, associated with the Date clan of Sendai. 締め (shime) means 'tightening' or 'fastening'. The belt is so named because it was considered a stylish accessory to keep the kimono neat.