the reason mange is right to left is because it's in japanese
the reason comics are left to right is because it's in english
japanese is read left to right just the same as english
mangas (as well as all books, magazines, etc.) are right to left because of an ancient writing format known as tategaki. it's taken from the chinese form of writing which went right to left, top to bottom.
modern japanese is written and read left to right, however, the formatting of mangas and books remains the same due to culture.
