The Green Mare, or Lady to be correct, is sometimes described from the Japanese as a Obake, a shapeshifter spirit.
The Green lady is describe to be covered in plants, such as moss and leaves, and sometimes seen as a lady with green fish like scales, jagged teeth, and seaweed like hair. In other versions of the story it is that she just has green skin.
She wanders around the Wahiawa gulch, the Wahiawa Botanical Garden, and sometimes the Wahiawa Elementary School.
The backstory for this ghost lady is that one day she and her two children were wondering around the Wahiawa gulch, when suddenly one of the kids got lost. The people there did try to help her, but slowly lost hope.
Soon after that, the lady said to die of a heartbreak, while in another similar story she went back to the gulch and never to be seen again.
The Green lady is active around day and night, and the smell of rotting plants near or in Wahiawa gulch means she is nearby. If she spotted another child, she would take them away, thinking the child must be hers.