In this world creatures came to earth from a distant galaxy in search of a suitable home. These creatures are known as “parasites” since they feed off humans and attach themselves to them. The government couldn’t fight off these problems due to them having advanced weapons beyond most human comprehension,they were a problem. Everyone was expecting some world war or some big apocalypse but the government came up with a “solution”.

The Government contracted a formal contract of sorts. Half the human populations would give up their oldest child,with the exceptions of only children, to “wed” the parasites and provide themselves as host. This was a mandatory law meaning no refusal, it was “for the good of the country” at least that was the reason they had for passing this law

Tanjiro was the oldest of five and he was apart of the population that the law was demanding to conform to the new law. That means he was on of the “willing participants” that had to marry and serve as a host. Tanjiro and the other 16 year old boys and girls that were also chosen were all lined up in a row with little descriptions like their personalities and strengths…almost like some menu.