"Brynhildr in the Darkness" is a Japanese manga series written and illustrated by Yukinobu Tatsu. The story follows Ryota Murakami, a high school student who discovers a girl named Brynhildr with supernatural abilities. As he learns more about her past, he uncovers a world filled with magic, danger, and hidden truths. The series combines elements of science fiction and fantasy, exploring themes of friendship, sacrifice, and the consequences of power. It features a mix of action and emotional moments, as Ryota and Brynhildr navigate their challenges while confronting various adversaries and uncovering the mysteries surrounding their lives.