u/Choice-Pin-888

I sadly do not remember the title of this anime, but I recall watching it on YouTube back in the door.

Details I am able to extract is that the anime is about an alien species that can infect the humans with their blood. The series switched protagonists, the 1st main character was a race car driver and the 2nd protagonist looks like Hei from Darker Than Black. Also, there was a green-haired scientist woman who gave a drug that can humans turn into an alien.