It is a series where Princess Luna writes into her diary every day after visiting Equestria. The reason why all the princesses are absent from Equestria is because of a dark force that threatens the Kingdom of Equestria. During the times of moderate inactivity against this dark force, the Princesses agree that Luna should be the one who should go to Equestria and tell the ponies of all the happenings and answer any questions they may have, due to the fact that Luna does not have many friends nor does she speak with the commoners too often. The Princesses knew that by making Luna do this, she will be able to make new friends and have new experiences.