The front (right photo) says chu-kon across the top (all writing is right to left). This means "the loyal dead", or "faithful spirits". Just below that is niku-dan-san-yu-shi, meaning "three brave men who were human bombs" (literally "meat-bombs-three-brave-guys").
During the First Shanghai Incident of 1932, three combat engineers made their way towards some Chinese barbed wire with a Bangalore torpedo, a long tubular bomb used for clearing a path through barbed wire. The thing exploded and killed them. They were immediately made into heroes for having valiantly sacrificed themselves to clear the way for their fellow soldiers. Many people nowadays believe it was an accident and they had no intention of killing themselves, but the story fit so well into the Japanese idea of total self-sacrifice that there was a whole industry making items immortalizing them .
On the back, the second line is go-koku-no-kami, "gods defending the country", an allusion to these men (great men were thought of as gods or kami after death).
The third line is 7-2-22 refers to the date, Showa 7, second month, 22nd day, i.e. February 22, 1932.
The last bit of writing is the family names of the three men written in three vertical columns: Enoshita, Kitagawa and Sakue.