The unnamed principal of Sainan High is well-known throughout campus as a pervert. He will impulsively enroll girls into the school body, so as to ogle and grope them without hindrance, though this is not restricted to Sainan High, but also occurs in public, as well.
An heir to a noble family line, Darcia became cursed along with the rest of his family when his grandfather attempted to artificially open the wolves' paradise with a machine. This curse, referred to as 'paradise sickness' throughout the anime, also affected Darcia's lover, Harmona, who is ths rendered into a state of perpetual sleep. Darcia kidnaps Cheza the flower maiden throughout the series to once again attempt to open the wolves' paradise and save himself and Harmona from their misery. He has mysterious powers that involve his wolf's eye, which allows him to turn into a wolf in the OVA. Written by NemoNowAndAlways
Tenkou is an evil, powerful man and the King of the Shitennou (Four Heaven Kings), who he controls and commands. He is even more powerful than Nakago, who served him, and even more evil. Tenkou believes he is a god, and it is his dream to attain the ultimate power of the "Shi Jin Ten Chi Sho", and become the ruler of both the book world and the real world. Tenkou is extremely powerful, merciless, and cruel. He kills people with no hesitation or remorse, and controls others, forcing them to acknowledge his superior powers. From linkFushigi Yuugi - The Fire of Suzaku's Wings
Gennai Hiraga was the original figure who destroyed the White House and appears multiple times throughout the series. He unleashes a mysterious power in the form of green lightning bolts which is used in the series to cut the entire electricity supply of New York City, disable aircraft and destroy buildings in Washington DC. In the final episode at the I-Jin fortress, Yomiko and Gennai engage in a swordfight, using a lightsabre-type weapon and a paper sword respectively. He dies when Yomiko uses a $100 bill to rupture a liquid nitrogen coolant line, whereupon he is frozen solid and shattered.
Hige seems to know how to function the best in human society, even wearing a dog collar, although the true meaning behind his collar is revealed later in the series that is a tag/transmitter . He tends to use his intuition more than the others, but only when he's not thinking with his stomach instead. Hige is quite the ladies' man and is always on the look-out for a nice girl. He has the best sense of smell between the others. Hige seems to be a Himalayan wolf in the series. (Source: Wikipedia) Hige's name means "beard" or "whiskers" in Japanese.
Nagisa is a boy raised as a girl.
An old school friend of Ryousuke's father.