The Sun Dormitory is the is one of Cross Academy's two Dormitories. The Sun Dorm is where the students of the Day Class live while the Night Class students study in the School Building. The Sun Dorm is divided into two separate buildings, the Girls Dorm and the Boys Dorm, unlike the Moon Dormitory where all of the Night Class students sleep in the same building. The Girls Dorm and the Boys Dorm both have a Representative or President, much like Kaname Kuran is the President of the Moon Dorm and the Night Class.
The Sun Dorm isn't as well furnished and decorated as the Moon Dorm, which looks like an aristocrat's mansion, but the Sun Dorm is given a more basic and somewhat humble look.