Umi’s and Dia’s voices are very similar! I kinda hate it how people compare Umi and Riko together or Dia and Eli together because they are nothing alike.

But anyways! Dia and Umi’s voices both very deep and strong, both of their voice rich and nice.

Umi’s voice is Rich, deep, like the deep dark blue sea. Her voice mainly focuses on power and blunt force like her personality, her voice is flexible and can be calm and soft at times.

Umi’s example video!  https://www.youtube.com/watch?

Dia’s voice deep, rich and also earthy, her voice is personally to me is refined and cool. But can sound more energetic/outgoing when she’s singing more upbeat songs. 

So both of their voices are deep, rich and cool

Dia’s example video! https://www.youtube.com/watch?