The Doctor is a Time Lord: a 900 year old alien with 2 hearts, part of a gifted civilization who mastered time travel. The Doctor saves planets for a living—more of a hobby actually, and the Doctor's very, very good at it.
100 years in the future, planetary colonization missions have begun as a necessity to help secure the survival of the human race. The first of these missions on a spacecraft known as Ark One encounters a catastrophic event causing massive destruction and loss of life. With more than a year left to go before reaching their target planet, a lack of life-sustaining supplies and loss of leadership, the remaining crew must become the best versions of themselves to stay on course and survive.
Manji is a crass, violent samurai with a special ability: he cannot die. Cursed with immortality by the nun Yobikuni as punishment for his ruthless deeds, he has grown weary of his ageless life. The only way to lift the curse is to slay 1,000 evil men. So Manji wanders Japan, shedding the blood of the wicked on his quest to finally die.
After resigning, a secret agent is abducted and taken to what looks like an idyllic village, but is really a bizarre Kafkaesque prison. His warders demand information. He gives them nothing, but only tries to escape.