A must read ! Wistoria has many plot holes and there are many things which dont make sense in the manga too . This Light novel ( 1 vol ) is prequel to the manga and narrates the actual story of Will and Elfaria in the orphanage and it follows till the part when they would go to the magic school and how Elfaria and Will parted . The entire backstory might not seem much in the manga ( i remember it being vague and dropping hints in different chapters ) but it goes very very deep in this light novel and you definitely gottaread this before going to the manga. There is just much stuff which makes you love other characters and know Will much more deeply .
The Illustrations are really good and i really loved the way author described each and every thing .

To be honest, this one is really depressing as it tends to go deeper and it just made me depressed . . .
There is much more information about the Guardians and the barrier .
This might make you depressed but it definitely plays a huge role in understanding all the troubles Elfaria and Will have gone through . You also get to see the previous Magia vander's.. All in all i recommend you to start reading the Light novel and then proceeding to the Manga , that way each and every thing makes much more sense and the series becomes much more Enjoyable.