Mark

Mark is the first son of Libra member K.K. and her husband Yukitoshi. He has a little brother named Cain who resembles their father but has a brash personality like their mother, while Mark himself resembles their mother and is more level-headed like their father. He is a responsible kid who fulfills his other brother role and tells K.K. not to get Cain's hopes high by making promises, knowing that her job often gets in the way.