Matantei Loki Ragnarok

If Mayura doesn't find a way to get a passing grade in her class, she'll end up having to stay after school to study which means: no more mysteries! While she and Narugami crack open the books, a wishing tree is growing from a gem dropped by Frey. Suddenly, Mayura gets an idea that will help her pass the tests; get one of the leaves from the wishing tree! But is it really that simple?