Gigaros was a male Cardian who appeared in episode 052. Ail and An realized that they were quickly running out of energy, so An suggested that this time they try to steal younger and "fresher" energy than before, so they called forth Gigaros. He immediately went to work attacking busses full of children and stealing their energy, beginning with students from Kari Kindergarten. Ail and An were quite amazed; the energy being collected was much stronger than that of their prior missions. The Makaiju was glowing with energy and life, and becoming stronger.
Soon, Luna discovered a newspaper with the headline, "Mysterious Attack on Kindergarten Bus?" She showed it to Rei, Makoto, and Ami, who were furious. Ami quickly used her mini computer to determine the next kindergarten that would be attacked. She said that there is 67% probability that the next one would be Shiba Kindergarten. Because Usagi was the only one who could use the disguise pen, they sent her to infiltrate the school's bus. Meanwhile, Minako was also at the school with her new friend, Mie Sayama. Mie was being bullied at school because of her belief in Sailor Moon. Minako went to talk to the children at school and tell them that Sailor Moon was real, although several remained skeptical. At the end of the day, the teacher announced that she would not be able to ride the bus that afternoon, so Minako volunteered to take her place. Usagi used her disguise pen to transform into a "sweet and stylish kindergarten teacher." She managed to slip onto the bus by claiming to be a new teacher. Although she was disguised, Minako recognized her instantly.
On the bus, Usagi and Minako led the children in singing the Sailor Moon theme song. When the bus went into a tunnel, Gigaros appeared in the middle of the road, then leapt through the window and onto the bus. The children were terrified, but Minako assured Mie that Sailor Moon would surely come to rescue them in a situation like this. Usagi overheard this and rushed towards Gigaros to attack him. The Cardian deftly pushed her away and out of the door, giving her the opportunity to transform into Sailor Moon when no one was looking. Gigaros prepared to attack the others when Sailor Moon appeared and stopped him. He quickly exited the bus to face her, then blasted her with a cyclone of energy. With the children distracted by the fight, Minako slipped away and transform into Sailor Venus. She attacked the Cardian with "Crescent Beam," briefly incapacitating him. Gigaros soon stood up, much to the dismay of Sailor Venus, who could not believe that her attack didn't destroy him. She used Crescent Beam again, but he easily deflected it. Both Senshi were knocked to the ground. When Gigaros prepared to attack again, the Moonlight Knight appeared and encouraged the girls to believe in themselves. Sailor Venus stood up and used a new attack, "Crescent Beam Shower." Several beams of light engulfed Gigaros, completely incapacitating him. Sailor Moon used the opportunity to attack with "Moon Princess Halation," destroying the Cardian once and for all.
Gigaros's name is a pun on the Japanese spelling of the name Icarus. Icarus was a character in Greek mythology who had man-made wings created with wax. In the well-known tale, Icarus soared too close to the sun and his waxen wings melted, causing him to fall into the sea and die. Gigaros's outfit - a toga-like garb with large wings - reflects his namesake.