Maria

Maria is a farm owner on the river who first appears in Episode 4 when Sister and Kou Ichinomiya go to get ingredients for "Stella's Welcoming cake".

Even though she has a beautiful appearance, she has a very harsh personality as she criticizes everyone she meets, for example, When she first met Kou, she said to him "Please don't talk, You'll just be wasting our world's precious oxygen". This leads Kou to freak out.

Trivia

 * The name Maria means "sea of bitterness" or "sea of sorrow".
 * However, some sources cite the alternative definitions of "rebellion", "wished-for child" and "mistress or lady of the sea".