The girl rescued a child who was almost run over for running a red light on a zebra crossing, but was also hit, causing her to lose all memories related to others.
When the interpersonal network built over the past seventeen years completely collapsed, the girl met "them".
"They" don't look like girls. "They" witnessed everything the girl experienced after losing her memory one by one, and also guided her to the final outcome.
"They" are not a girl's illusory fantasies, nor are they dreams turned into reality.
They are just people living in fantasy.