Yamada is at the dojo, mediating with the sensei and others at the end of class. When abruptly they found themselves abducted into another world. With other people -- some in groups and some as individuals -- one of them, a black man in digital camouflage, asks what's going on, and Yamada realizes the man is speaking in English, and he's hearing him in Japanese.
A demon reveals that it's brought them here for his amusement. Other people greet them and explain that the demon brings them new people if they sacrifice goods for it -- and if they don't, they will die out -- and well, when the first people arrived here, they found an abandoned village.
They reveal the Skill Sphere, which grants everyone who touches a skill -- rather like a video game. (The resemblance to a game is commented on many times.) Yamada is the Kamikaze of the title, which will boost his fighting at the cost of his sense.
And the story goes on, heavy on the logic of what would really happen in such a world. Boot camp training -- Sensei wisely observes that they are taught to obey orders precisely under stress. The minimal level of subsistence the non-military people are able to bring them to. The limits of real world training in the dungeon where they must bring the fight (or the monsters come after them). The illogic of their ability to mine ores that would not be in such close proximity. The powers that various religious people acquire -- Shinto, Buddhist and Christian, with the theological implications brushed on little -- they are after all living so close to the edge that they can't stand infighting. And more.