What kind of detail is the 'bijo' mentioned in the product descriptions?

Sleeve ends, and hems. In LOW CLASSIC product descriptions, the word bijo mainly appears in these two places^[1][2].

Bijo is used to refer to a narrow, strap-like adjustment piece attached to clothing. It is close to imagining a short strap attached to the outside of a shirt sleeve, or a small belt that cinches the cuff of a coat sleeve. Since a strap alone cannot fasten, it usually pairs with a closure hardware such as a button or snap, and the circumference changes depending on which hole it is fastened to. The explanation that a sleeve can be styled with different sleeve silhouettes because it has both a bijo and buttons refers precisely to this structure^[3].

When placed at the hem, the principle is no different. However, regarding the hem bijo, it is only confirmed that the detail exists, and which closure hardware it is used with must be checked separately for each product^[4].

hmmm, the places where a bijo is attached are all points where a garment ends. Since sleeve ends and hems are where the width of a garment is finalized, placing an adjustment feature here makes quite a difference in impression depending on whether it is cinched or left loose, even when wearing the same clothing.