Fortunately, now that he is a soldier, he is not restricted to one world. He has access to the races of every world that the Yggdrasil civilization has subdued.
As long as he has the merit points and the necessary security level to access some sensitive races, then he can have any race that he wants.
One of the sensitive races is the vampire race. The higher vampires and primordial vampires, which were not available at the black market, are available for exchange here.
With the hugger vampires, he can gain the ability to hypnotize and enslave others. With the primordial vampires, he can gain the ability to create more vampires.
Unfortunately, he can't get them yet because not only are they expensive, but they also require army ranks of three and four stars before he can exchange for the higher and primordial vampires, respectively.