Board Thread:General Discussion/@comment-71.232.131.59-20131205143653/@comment-71.47.224.200-20140611213606
From Katawa Shoujo Wiki
I've always thought she had a few mental disabilities - dyslexia, ADHD, OCD and quite possibly being autistic. My friend's certain that she has a problem with her inner ear and that's why she's learning sign language - preparation for the future in case she loses her hearing entirely.
