Centuries ago, the Akita was owned only by the Shogun, the imperial leaders of the century. The dogs were used to track large game and hold it at bay until the hunters arrived to make the kill.
Akitas were introduced to the U.S. by serviceman returning from Japan after World War II.
As to what they're good for in Japan? I dunno, but I do love this story:
Hachi-Ko was one of the most revered Japanese Akitas of all time. Hachi-Ko was owned by Professor Eizaburo Ueno of Tokyo. Everyday the Professor would commute to work on the the train from Shibuya Station. Hachi-Ko would accompany his master to the station each morning and meet him and accompany him home each night.
On May 25, 1925, when the dog was 18 months old, he waited for his master's arrival on the four o'clock train. But he waited in vain; Professor Ueno had suffered a fatal stroke at work. Hachi-Ko continued to wait for his master's return. He traveled to and from the station each day for the next nine years. He allowed the professor's relatives to care for him, but he never gave up his vigil at the station for his master. His vigil became world renowned, and shortly after his death, a bronze statue was erected at the train station in his honor.
Now that was a devoted companion.