Izayoi's makeup

Izayoi's lip-coloring makeup was a beauty product that she used to apply colour, texture, and protection to the lips.

History
Being born in a wealthy/noble family, it is possible that Izayoi inherited the makeup from her mother or any other women born in the family, probably along with the other makeup kit. Izayoi used the lip-coloring makeup before going outside into public places when she was alive, even before and after the birth of her only son.

After dying, Izayoi left Inuyasha with two things from her as a memento: the makeup itself along with his Robe of the Fire-Rat. Some time later, Inuyasha gave the makeup to his first love, Kikyō.

Fifty years after the death of Kikyō, it is possible that Inuyasha found the makeup among Kikyō's other possessions and claimed it back.

Years later, the makeup ended up in the possession of Inuyasha's only daughter Moroha, which is used to hide one the Rainbow Pearls.

Trivia

 * It is customarily since ancient times for women (at first for noble women, later for common women as well) to use cosmetics, including lip-coloring makeups.
 * It was never explained how Inuyasha got Izayoi's makeup back.
 * It is a possibility that Moroha keeps the makeup as a memento of her mother.