The Servant of Death - Version 0.5 by Little Huntress Team Win/Mac/Linux - Adult Sex Game

The protagonist of this story is dying, because of an incurable sickness.
In reality this condition is incurable by science only, luckily our protagonist is always into the occult so he goes for this last chance.
He needs to summon and make a pact with 3 mythical creatures if he wants to stay alive.
This game is about how he does this with the first one, which is a fairy named Silia.