Helena was an infiltration type Intelligence Army Warrior Beast who was the principle antagonist on Ep.37 of the Great Mazinger Anime - she was one a few female Beasts in the show, and also among a few to have dialogue. Her body was largely magenta and black in color, with a lavender color hair and light yellow eyes and ears, antenna coming out of these, and she wore a light blue cape, a necklace and a dark red belt with light yellow rivets and heart shape buckle. She had the ability to manipulate her size, as well take the appearance of any women. She had considerable strength, and fire lasers from her eyes. She could also fire a Heat beam from her heart shape belt buckle (and yes, it did so in the shape of hearts) and release spikes from the bottom of her boots. Her brain was incorporated in the head.

When the Empire learns that an American Scientist named Karen, who is from the university where Koji and Sayaka went to study, is coming to visit the Science Fortress, The Great Marshall of Hell decides to go along to see things through, despite the mission been led by the Intelligence Army. As Karen's plane is been watch, Janus drafts Helena who takes the form of Jun to rendezvous and kidnap Karen in the airport, while Janus causes an avalanche, forcing Jun and Shiro to take a detour. When Karen arrives she finds Jun (Helena in her disguise) and takes her and leave the airport just before Shiro and the Real Jun arrive.

Along the way, Helena gets rid of Karen, throwing her off a cliff, as Janus sends Trucks with Boxes. Helena rendezvous with the trucks and continues to the lab where she is receive by the Kabuto Tetsuya - “Karen” asks Tetsuya to unload the boxes, been gift from Koji, but ask to not have them unpacked until tomorrow, all of it been a surprise. Shiro and Jun are recall back to the lab, where they welcome “Karen” and have a dinner party for her, but Tetsuya notices that her hands sparkle when cutting a steak with knife a fork, this causes suspicions out of him and “Karen” notices, taking her leave back to her guest room.

Not far from the the Borot Hangar, the gang finds the Real Karen, harm and unconscious - they take her in and bring a doctor to treat her while Helena informs the rest of Catlops Corps, all hiding in the boxes, to proceed to attack at 3AM - she is surprise by Tetsuya and Jun who ask her why she was in the supply room to which replies she was inspecting the gifts, and asks them in return why where they following her.

Meanwhile knowledge of the real Karen's survival comes to Janus, who sends her Catlops Corp to finish her and the Borot Gang off – at that moment the real Karen wakes up and warns the gang of the perils in the fortress, Boss tries to leave and warned them but his blocked by Janus and her Party. Boss makes a run for it, but is shutdown by Janus, while Nuke and Mucha board the Borot and make a stand, Janus orders Karen to attack, and the Soldiers in he boxes come out, attacking the staff. Boss calls via radio and Tetsuya flies on the Brain Condor to assist, clearing off the the Corp. Janus request for help where denied by the Marshall as he was only present as an observer.

Helena and her group enter into the Kabutos room and blast off the bed, only to discovered these empty, then are corner by Jun who fires at them and a standoff ensues. Kenzo and Shiro try to sneak out but Helena kidnaps Shiro and makes a run for it. Kenzo warns Tetsuya, and when he finds them Helena removes her disguise and shows her true giant form. She throws her challenge and Tetsuya launches Great Mazinger to rescue Shiro, but Tetsuya uses restrain, as Janus is uses Shiro as hostage. Helena takes the advantage by firing her Heart Beam, kicks him down and then grabs Great by the legs, bashing him over onto the ground. Jun arrives on the Queen Star, and Tetsuya uses the great sword, Helena avoids, cutting the tree where Shiro was dangling, but Jun save Shiro mid air and flies off. Helena tries then to overheat Great, but he grabs her and tosses her into the air – Tetsuya finishes her off with Knee Impulse Kick and Backspin kick, cutting her in half and making it exploded. Janus berates the Great Marshall for his refusal to provide assistance, though he orders her to hold her tongue.

In the end, the real Karen meets the staff and is eager to share Shiro of news from Koji.