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A quest character from Elona. In an "homage" to BioShock, Little Sisters are capturable characters found by killing rarely spawning Big Daddy monsters, and can be returned to the Strange Scientist for rare items. (Specifically, they are captured with "Little Balls", which are special Little Sister-only pokeballs in an homage to Pokemon.) Because the items you get for the quest include duplicates of otherwise unique objects gained from other quests, they are extremely valuable. Also in homage to the game, killing and eating a Little Sister grants the player extra Life, Mana, and skill potential, but counts as a "debt" of sisters you need to rescue to gain the rare items. (This also counts if the little sister dies when you didn't kill her, yourself.)
They have black hair in a bob cut or hime cut, depending on the artist, and wear a red dress.
Not to be confused with the similarly-named Younger Sister.