Hiroko was a fair-skinned girl with shoulder-length dark brown hair tied in two pigtails. She had big, round glasses and wearing casual clothing, such as long-sleeved sweaters and shorts. Her emblem was a heavy teardrop-spoke asterisk.
Hiroko was a very sociable, friendly and cheerful girl who was usually shy, but when she gains people's trust, she was very expressive.
She was also kind as when Sakura Sakaki called her stick "crappy" she didn't mind and just continued explaining her situation.
- The name Hiroko means "command, esteem" (博) (hiro) and "child" (子) (ko).
- Hiroko's surname Shimozono means "frost" (霜) (shimo) and "garden" (園) (sono/zono).
- When it is written in different kanji, Shimo can mean "under, below" (下) while Shi can mean death (死) and four (四).
- Hiroko willingly let Kayo Komura copy her stick, but on the condition her and Kayo, as well as Sakura Sakaki, could be friends.
- Hiroko says she uses her stick to make her bullies stay away from her, but no one wants to be her friend at a cost.
- Hiroko made her debut anime appearance in the Episode 6, although it was a cameo, she was one of the many girls who appeared in the photographs.
- Hiroko re-appeared in the Chapter 116 but was killed by the Administrators with other magical girls in the Chapter 120.
- In the Chapter 116, Hiroko was mistakenly called Noriko.
- She was given the nickname Noroko.