A small amount of human blood is all we need.

Saving the many means leaving the few to perish.

Manipulating a small object requires only a small amount of aura. A large object requires a larger amount of aura.

Yushirou can get by with even less blood.

My armor is composed of adamantite.

but they gradually increased the amount more and more over time.

First is the ""Velvet Lechance"" which is a mixture of blackberry, honey, spiced wine and a touch of nightshade... perfectly safe, I assure you.

Drops of blood on the pillow. Trail of 'em leading to the window.

Monkshood, for instance - lovely blossom, soothes aches and pains, but just a handful and you could poison a whole family. A very useful plant.