Dina is a character featured within The Minish Cap. She is one of the teachers at Funday School and is the twin sister of Tina. For much of the game, Dina can be seen standing just outside of Funday School and acts as a blockade, preventing Link from entering the school. She states that a very important class is going on right now and she cannot let Link in.
Dina has nearly an identical sprite image as her sister Tina, with the only difference being that Tina wears a purple dress and has purple hair, where as Dina has a red dress and has green hair.
Dina is never actually mentioned by name at all anywhere in the game. However, in the game's text, there is a character named Dina. Given she is the twin sister is Tina and they are both teachers, along with no other characters named Dina, it is very likely she is Dina.