As far as I was able to dig, no one is left. I'll make another pass to check.
It looks like she may have deleted her facebook
Then you will change the search from looking for Aibou to looking for all her friends from 2009 onwards. If you can't find them, then keep digging by looking at the internet archive for posts that have links to the facebook pages of their friends. As you uncover more people, they may be able to point you to other more recent sources. Or one of them might finally say "Aibou relented from her hate of Warcraft and finally created an account there with the name Ai Oboeteimasuka" or whatever other lead you may get. As I said before, your real hunt is not for her, but for all the people around her.
Certainly, the records exist at warpportal. But you'll have to contact the CIA if you want to know. Whenever I forget my passwords, I shoot off a quick request to CIA.GOV and they tell me all my passwords that I forgot.
Remembered Life Story: One day while chatting, she talked to you about her volunteering at the local food bank for November 2007. --> there are only so many food banks in that town, so you probably know which one if you searched.
Remembered Online Activity: One day while chatting, she talked to you about how she edited a page at wikipedia on Olive Oil and how she posted about fake oil. She commented about posting a link to a PDF. --> time for you to check which account name posted that PDF
Remembered Situation: One day, Aibou talked about editing a page at IROWIKI for the Blank Card In Mouth gear. --> these page records are gone from the current site, but Bluenesssss might have the names AND VERIFICATION EMAIL ADDRESS of accounts back then.
If you still have the hard drives from your OLD PC or laptop from 2004 to 2008, then you can try to search through the file records for her contact IP address and linked name. If she had a website, it would possibly still be listed in INDEX.DAT or whatever similar file other browser types use. Some sites save searches as URLs so that INDEX.DAT could potentially have the url with a phone number if you ever absentmindedly did a search based on phone number. I'm not saying that is rational or actually searchable, but I am just grasping at straws for ideas on what you could have done back then. There are tools to dig thru those.
May the Fabre be with you.
*sorry for the bad star wars pun*