GANTZ/EXA

The main character is named Nagatomo, he is an astronaut and a scientist in charge of a secret operation about experimenting cryogenics on human subjects such a assasins or political prisoners, all inside a spaceship called "RETRO." Suddenly he wakes up inside the ship only to see outside a huge amount of black spheres floating in space, he first believes they could the debris of something, then he realizes there is life activity inside them and leaves the ship to bring one of those spheres insi...