Shiori's father, Tsukuyomaru, came from a bat-demon clan that preyed on the blood of humans and animals; Shiori's mother's village was one of their hunting grounds; however, Tsukuyomaru was different than the others—he did not kill humans, eventually meeting Shizu and falling in love with her. After Shiori was born, the attacks ceased and the village was at peace until the untimely death of Tsukuyomaru.
In attempts to stop the attacks on the village, Shizu, Shiori's mother agreed to offer Shiori to her grandfather, Taigokumaru. Shiori at first refuses to leave as she was afraid of him but by the persuasion of the villagers she left hesitantly to Taigokumaru's side.
Like Inuyasha, Shiori was bullied constantly throughout her childhood for being a half-demon despite the obvious peace that Tsukuyomaru had brought to Shiori's village. Her mother too was discriminated against and they both lived secluded from the rest of the village which showed how ungrateful the villagers had showed for the kindness that Tsukuyomaru had showed to them. When Taigokumaru broke his promise, the villagers attacked Shiori's mother only to be stopped by Inuyasha and his friends.
Shiori, like her father and grandfather, has the ability to create barriers from a red orb, called the Blood Coral Crystal. This skill and duty is passed down from generation to generation as the ability to create barriers wanes with age and the ability is lost once the duty has been passed to someone else. The barriers created by the bat demons are impenetrable and even deflected Tessaiga's Kaze no Kizu and withstand the Backlash Wave.
(Source: Inuyasha Wikia)
