After reading the Ch. 220 scanlation, I found a little more about Asuna's past. Rakan tells Negi the truth about the origins of Asuna's magic cancelling power. Asuna finally turns out to be between 25 and 27 years old. Rakan did told Negi about his feelings of what happen to Ostia. Rakan had thought that Nagi did not care about one particular little girl.
Oddly, Nagi would allow Asuna to start traveling with the Al Rubra.
In Ch. 169, Asuna seem to have been use as a weapon of last resort. Yet, Nagi and the Al Rubra arrived on time. The details of Ch. 169 are a little confusing. Only Eishun and Al were Nagi during the rescue attempt. The Generals seem to be confused over what is happening at first.
Asuna's past before 1993 is part of a greater mystery. A mystery like Nagi's disappearance. Rakan tells Negi not to focus on Asuna's past, but to focus only on the present and protecting her.
