|The Girl in the Blue Dress|
She seems... Familiar somehow
She clearly has some sort of connection with the protagonist, but their relationship is vague at best, and speculative at worst. Your first encounter with the girl will be while exploring the apartment.
It is possible that the Girl in the Blue Dress is Chie
This girl is a reflection of distorted memories of "you" about "your" girlfriend/sister who died in hospital after bus explosion. When you try to interact with "girl in blue dress" she says "I didn't want you to find me, not like that" and vanishes - these presuembly were her words when "you" last seen her (according to green ending), after which she "vanished" from real world (died).