[ Ah. Now Astolfo feels a little embarrassed! He has to explain mana transfers to this innocent maiden! To his Master, who's really cute and earnest and doing her best for all of them! ]

Ah, well. You see all humans have mana in them and you can transfer it using rituals. And... it's also in bodily fluids. Like blood. And other things.

[ Cough. Astolfo is pretty shameless but this is an awkward talk. ]