Hence the Shueisha guides are an important supporting source for canon in the Digimon fandom, and the amusing illustrations help too. The structure of each Pendulum guide is generally similar. At the beginning they introduce three principle characters based on the attributes of Vaccine, Data, and Virus. In 3.5 these are Wakuji, Dayta, and Vire, derived from wakuchin (vaccine) and shitsuji (butler), deeta (data) and 太 ta (grand), and from wairusu (virus). In 5.5 these are Wakuta, Data X, and Virchi. These characters serve as the player's narrators for the different sections of the guidebooks.
Keibunsha's utterly fail to. Having access to the official sources and sanction of Bandai works in Shueisha's favor; nowhere else will you find Folder Continent broken down by field in this level of detail. For the Japanese literate the Shueisha guides are a really fun read, though I personally find Metal Empire to have a better handle on the lore than Nightmare Soldiers. ME actually lays out the entire Folder Continent and where each field originates from.
It's particularly disappointing coming from 5.5 guide because it was launched at the end of the Pendulum's life. I guess that'll just have to wait for when my Perfect Training guide arrives!
The books are quite small, measuring just 6.1 x 4.2 x 0.3 inches. But the amount of detail crammed in is impressive. Unfortunately, these guides have acquired something of a collector's value over time, and the prices have been artificially driven up by secondhand sellers in Japan. At this moment the Digimon Pendulum 1.5: Nature Spirits guide is available for a rare $15 low through Amazon, but be aware that depending on your location shipping could climb up as high as to double the price.