Syoko is an introverted girl with a passion for mushrooms (which also includes growing them). She is also awkward and lacks communication skills, and often stutters when talking. She only became an idol after being coerced into going to an audition to find less conventional idols by the Producer. However, her personality changes radically once she turns into an idol.
After training, she sports a total makeover, adopting a death metal look and becoming unhinged. Fans often assume that Syoko might have eaten too many mushrooms, which resulted in her erratic behavior. Although, some fans also argue that her personality actually remained the same and her erratic behavior is only an act designed specifically for her idol persona. The latter seems less likely, due to the fact that in Starlight Stage she snaps out of extreme stress during her audition to become an idol and slips into her death metal personality.
(Source: iM@S Wiki)