You might have noticed that the book tends to promote old-world values and beliefs over those of the modern world. Todd Wainio's story very clearly states that old-school military tactics needed to be adopted to fend off the deadhead army. David Allen Forbes's story hints at the importance of cherishing the foundations of the past, be they castles or the British monarchy.
And the stories of Kondo Tatsumi and Sensei Tomonaga Ijiro embody this triumphing of old over new more than any other.
Picture any cyberspace nerd from any Hollywood blockbuster, and you've got Kondo Tatsumi in a nutshell. The kid's disconnect from the real world is so severe that he doesn't even notice the entire country of Japan collapsing around him. As he notes, "I didn't live in Japan. I lived in a world of free-floating information" (7.4.11). Kondo very clearly represents new-world values in this equation.
When the real world comes knocking in the form of a zombified neighbor, Kondo is horribly unprepared for the crisis. He has no weapons and no friends or family to rely on. He only survives because the old world comes to his aid (symbolically, of course).
The first time is when a traditional kamidana—or Shinto shrine—warns him of an incoming zombie attack. The second time is in the form of a katana sword, the traditional weapon of the Japanese samurai. This weapon allows him to escape his apartment complex.
On the other side of this character equation is Ijiro, proprietor of old-world values. He prays to the gods—or kami—regularly. He takes care of the land by burying the dead zombies. He also lives his life by a traditional Japanese honor system. Initially, he tries to commit honorable suicide, but later devotes himself to pleasing the gods by killing him some zombies (7.521).
Ijiro's old world values and lifestyle provide him the ability to defend himself against the zombies. And Kondo can only survive the zombie onslaught by literally taking up the traditional weapons of Japan's past.
When these two meet, it's literally a connecting of the old world and the new. In chapter 9.9, Kondo notes that this is the best thing that could have happened to either them, or Japan:
[Ijiro's] generation wanted to rule the world, and mine was content to let the world, and by the world I mean your country, rule us. Both paths led to the near destruction of our homeland. There has to be a better way, a middle path where we take responsibility for our own protection, but not so much that it inspires anxiety and hatred among our fellow nations. (9.9.3)
By bringing together Kondo's modern world knowledge and Ijiro's old-world values, Japan finds that middle ground between old and new. In fact, the other countries that survive the zombie war—like American and Britain—all find this middle path while those that don't fare so well (ahem, Russia) ignore the middle ground for one extreme or the other.
At least, that's what the novel seems to promote. But it's worth noting that Kondo seems more altered to fit old world values than Ijiro is changed to meet modern world expectations. Kondo goes from an acne-spotted cyber geek to a "clean-shaven, tanned and toned" soldier (7.4.1). But we never seen any modern day tools changing Ijiro. In fact, the rejection of the modern world seems to only help the old hermit.
Ultimately, we can't decide where the book really lands with these two. Is the old world value system seen as better, or does it truly reach a middle ground?