Mini Goddess
That should be
Ah, My Goddess: Mini-Goddesses
Also, Rob, there's not 13 episodes. There's 48. Off MAC's official site.
Item Code : MA222E
Quantity : 3 Discs
Dialogue : Japanese/English
Subtitle : English/Off
Region : All Region, Free Code
Disc Type : DVD-9 × 1, DVD-5 × 2
Screen : 4:3 Letter Box
Audio : Hi-Fi
Series Type : TV Series
System : Ntsc
Episodes : 1-48
Running Time : 325 Mins