In human form, Thancrus appears to be an Asian male with black hair and a slender build.
In the comic books and the 2005 anime, Thancrus and the Hyper-Zoanoid Team Five appear when Sho Fukamachi and Agito Makishima attempt to infiltrate Cronos's Mount Minakami base to rescue Sho's father Fumio. The Hyper-Zoanoids engage Guyver-III while Sho rescues his father, and Agito is knocked into a ravine by Elegen. Believing Agito to be defeated, Team Five are taken completely by surprise when Guyver-III emerges from the ground behind them, slicing Thancrus in half with his sonic swords.
In the 12-part series' fourth episode "Attack Of The Hyper-Zoanoid Team Five", Team Five attack Sho Fukamachi's school in order to draw him out. Thancrus engages the Guyver in combat, cutting him many times. As he is about to deal a finishing blow, Sho blocks him with his own vibration blade. The vibrations from Sho's and Thancrus's blades making contact produces ultrasonic noise that nearly deafens Sho's friends who are nearby. Thancrus jumps back from Sho but is then suddenly engulfed in an energy beam fired from above and vaporized. Sho and the other Hyper-Zoanoids look up to find Guyver-III standing on the school rooftop with half his chestplate open, apparently having used his Mega-Smasher to destroy Thancrus.