Throughout Suikoden 2, Nanami is willing to put her life on the line for you. She forces her way into the group several times so she can look after you, and her reason for faking her death at the end of the game is because of the way you tried to protect her from the arrows that were being shot by the Matilda knights.
When you first encounter Neclord and he raises corpses from the ground, Nanami runs behind you and says "Riou is gonna get you!"
So she'll take on human soldiers and knights to protect her little brother, but when it comes to a creepy vampire and his zombies, she'll hide behind him and let him do the fighting?
Or does Nanami have some sort of necrophobia when it comes to undead beings? She seemed pretty terrified of the Wandering Ghost myth when we were staying at the Greenhill dorms.