This is one of several "Mr. Hook" cartoons made to encourage soldiers to buy war bonds. In this installment, the film begins in Tokyo, with Tokyo Rose and her evil friends broadcasting propaganda to the Allied servicemen. When the message reaches Hook's ship, he's incensed when Rose suggests that war bonds are a waste of money, so he sends a little "surprise package" her way. Then, following this, you see all the great ways that these bonds will pay off when the war has completed--nice clothes, a nice car and some spending money--everything a guy on the prowl for a "hot tomato" needs!
By today's standards, this is a very shocking film. After all, the stereotypes of the Japanese are rather racist. However, as long as the viewer actually understands why the enemy was portrayed this way and the context for the film, it's still an enjoyable film--plus it really helps to make the message clear to soldiers and sailors.
By the way, this was not intended to be seen by the general public but only by servicemen. In order to save money, unlike other Warner Brothers cartoons, this one is in black & white--a money-saving maneuver.