A Wish Upon a Negai is about a girl named Khloe and her connection with a mythical creature called a Negai. Khloe had grown up listening to tales, told by her grandma, about Negais, magical creatures that will grant wishes to those who are pure of heart. Negais are majestical big cats with creamy fur that is cooler than ice, and only those who are pure of heart see their big cat form. Khloe finds joy in her conversations with her grandma because it comforts her in times of mourning as her mum is terminally sick and her brother and father are at war. Fast forward to a stark, doleful day, Khloe is 15 years old and at her grandmother's funeral. On her way back from it, she collapses from exhaustion and awakens at a stranger's house. After talking to the stranger, whose name is Noah, she realizes that he is going to Antarctica - where the Negais reside - soon. In desperation, Khloe begs Noah to let her come with him. Dubiously, Noah agrees. Khloe is delighted, but one question remains: Will Khloe find happiness during her dreadful times through wishes granted by the Negai? Or will she be shunned away if she isn't pure of heart?