Manaka Kisaragi is a highly-evolved being with the ability to draw memories from her surroundings in the form of butterflies of light. She was given the Towa drug by Dr Kisugi as an unborn child, which caused her abilities to develop. The "devil's child", as she was known, was killed by her dying grandmother. Echoes' light brought Manaka back to life and caused accelerated aging. Her grandmother died soon after. Her insight into people's memories makes her aware of Echoes, whom she emulates.

[Wikipedia]