Since this word is made up of a single kanji, it should use the kun'yomi reading. When learning the kanji, you didn't learn that reading, so here's a mnemonic to help you with this word:
Think about the south. What's down there? Mean Amy (みなみ) lives down there. Think of the last mean thing she did to you and imagine it while yelling out "MEAN AMYYYYY" at the sky.
There is a police station on the south side of the library.
Why isn't there a North Japan Railway Company and a South Japan Railway Company, even though there's an East Japan Railway Company and a West Japan Railway Company?
I saw Brad Pitt at the south baseball stadium.