A Tokyo native, Kita was the second son of famous poet Mokichi Saito, who was also a psychiatrist.
A graduate of Tohoku University's School of Medicine, Kita initially worked as a doctor at Keio University Hospital. Motivated by the collections of his father's poems and the books of German author Thomas Mann, he decided to become a novelist.
In 1960, Kita published the essay, "Dr. Mambo at Sea," an account of his experiences working as a doctor traveling the world on a Fisheries Agency research ship. It became a best-seller.
That year, he also published "In the Corner of Night and Fog," a novel that depicts the tragic story of a psychiatrist amid Nazi Germany's "Nacht und Nebel" (Night and Fog), a campaign to catch anti-Nazi activists and members of the resistance movement. He won the Akutagawa Prize for the book the same year.
His other major novels include "Ghosts," published in 1954 and "Under a Shining Blue Sky," which appeared in 1982. He is also renowned for four biographical installments of his father Mokichi's life, for which he was awarded the Osaragi Jiro Prize in 1998.
His most famous novel, "The House of Nire," follows three generations of the Nire family, which runs a large psychiatric hospital in Tokyo. The story is modeled on Kita's own family, with both his grandfather and father working as doctors.
Being an aficionado of the Hanshin Tigers baseball club, he also published a humorous essay on his passion for the team.
His elder brother was Shigeta Saito, a psychiatrist-cum-essayist who died in 2006. His daughter, Yuka Saito, is also an essayist.