A number of themes — war, violence, nature, sacrifice, and boundaries — are woven together in the overriding theme of the book, Muldrow's quest.
His trip from a sewer pipe in Tokyo to a blood-and-feathered last stand on Hokkaido constitutes not only the framework for the book but a major theme, as Muldrow, in a long tradition of heroes from Odysseus to Don Quixote, must overcome obstacles to achieve his goal. Muldrow's quest is unique because it is extraordinary; he does not just want to survive, he wants to travel through his enemy's heartland and gain his freedom.
Like other heroes, Muldrow is transformed by his quest. The war propels him to dire circumstances, violence both aggrieves and sustains him, and his own nature shifts as quickly as the terrain under his feet, as he moves from instinctive behavior to thoughtful reflection to nostalgia.