Soul Essence

Soul Essence is the substance that Dhampirs feed on. It is present in all bodily fluids, but is most apparent in blood. Sweat contains the least amount of Soul Essence. If too much is taken out, that person can be reduced to dust as shown in Light Novel Volume 6, when a Ghost nearly dies from being bitten by a Dhampir.

When Sora and Shiro first meet Plum, he licks the sweat off the bottom of Shiro's foot in order to avoid dying of starvation.

Soul Essence