Chara Friedrich has had this look since September 15, 2000.
She is using a ribbon that Toriel made as a birthday present.
To be precise, it is a ribbon attached to a rubber band. The rubber was smuggled out of the rebel-occupied territories by partisans on the government side.
It is treated as a "cursed object" because it is soaked with magic power and its quality has been improved.
The quality of the rubber has been improved to such an extent that Toriel said, "It will last until Chara grows old and dies.