Big Gun

(from ebookjapan):

Billy Holiday, the greatest gunfighter in the Wild West, has left his past behind and married the daughter of an Indian. The triplet outlaw Jason brothers come to town and set their sights on him.

In addition to the title story, "Big Gun," this collection includes three short stories, "Chasing Across 25,000 Miles", "A White Summer's Day", and "Hitotsuki Hanjiro".