Riddle Story of Devil anime
Tokaku Azuma, a top-ranked private girls’ boarding school, has just transferred to Myoujou Academy. There’s a catch. She is part of a group of 11 students from Class Black who are attempting to assassinate Haru Ichinose, their sweet-natured classmate. Anybody who succeeds in this challenge will receive their deepest desires, regardless of the cost or difficulty. Each assassin has one chance to succeed. If they fail to kill her they will be expelled.
Tokaku chooses to pursue a different path despite the incredible reward. Despite Haru being her target, Tokaku soon falls for the girl she was supposed to kill. Haru is the target of Haru’s entire class. Tokaku vows to protect Haru from her growing bloodlust and refuses to let Haru die.