Hye-rim

Ever since she was young Hye-rim has had a perfect memory. Whatever she learned she retained, even after only hearing/seeing it once. Her 'talent' caused her to become an outcast with others and people often just used her for her ability. The massive knowledge she kept inside her head, along with her natural distrust of people made her extremely irritable and anti-social. This was how she acted until one day she got into an accident, causing something to disconnect inside her head and making her lose her photographic memory.

While the knowledge is still somewhere in her mind, she can no longer immediately recall things like she used to. This also caused her personality to do a complete 180 and she's now one of the most cheerful, bubbly people ever.