It is explained to the audience that Liru is a werewolf and dislikes silver. Liru has an energetic personality and has animal traits such as the ability to leap great distances with little effort. Like all werewolves, she is lycanthropic; her wolf form looks similar to a yellow puppy. A minor reocurring theme in the episodes is when Liru sees a full moon shaped object, she immediately changes into her lycan form (though strangely enough she seems somewhat resilient to the real moon's effects).

Source:Wikipedia