Demon Astronaut

exposure to sunlight or stellar material can destroy him. he can regenerate entire limbs instantly and no injury can kill him. only sunlight or the sword of a demon slayer can. the year is 3111 and humanity has spread across the galaxy. the only thing that threatens the existence is demons. demons inhabit almost all planets and only come out at night. they eat humans and masacre entire colonies. the demon slayers kill demons by scooping up solar energy with their special starships and dumping it over the night side of infected planets. The galaxy's most skilled demon slayer was named tanjiro. he first became a Demon Slayer in the 1920s after his family was eaten by a demon. his sister, nezuko, was turned into a demon the same night their family was killed. he spent years trying to find a way to turn his sister back into a human, which he eventually succeeds. when tanjiro was lying on his death bed, the world health organisation found a way to not only cure aging, but completely reverse it. tanjiro has spent the past 1100 years slaying demons to protect humanity. purging world after world along side his half demon sister.