Ta-Nehisi Coates is just getting started with Marvel Comics' "Black Panther."

His run, which started in April, is up to its fifth issue, with the first four collected in a volume that's currently for sale in comics shops and will be more widely available next week. Originally, Coates, who won the National Book Award for his 2015 book "Between the World and Me," signed on to write 12 issues but recently received approval to write a dozen more. If he has his way, he will be writing the book for many more...