I have no idea who the author of 'dal night novel' is. There are so many novels out there, and without more context, it's impossible to determine the author.
Well, without more information, it's difficult to say precisely. But generally, a 'dal night novel' could potentially be a work of fiction that uses the night in a place called Dal as a backdrop. It could explore themes like the hidden side of the town or the different personalities that emerge after sunset. There could be elements of suspense if it involves things that only happen at night, like a secret society that meets during the dark hours or strange occurrences that disrupt the normal night - time routine in Dal.
I'm not entirely sure as it could be various things. It might be a visual novel that has some sort of recurring or 'dal segno' (from the sign in music notation which means to repeat from a certain point) element in its story or gameplay.
I'm not aware of any specifically popular 'dal segno visual novel' titles off - hand. It might be a relatively niche concept within the visual novel world.