Ondai (spelled Ondaï in French) is a robot that looks like a cylinder and walks on three flat metal legs. He is very analytical and constantly running calculations, but is also known to have a sarcastic and narcissistic personality.
Ondai's star-racer is capable of transforming into a humanoid mech armed with a pair of energy swords and a battery of missile launchers. He may sometimes get carried away with calculations when too many things around him are mathematically possible, causing him to go into a state of awe, as was exemplified in Optimised Like Ondai.
In Secret Like Sul, Ondai forms a temporary alliance with Prince Aikka, Ning and Skun to remove Sul from the race. According to Ondai, Sul is both the most powerful and unpredictable pilot, and agrees to the alliance when he calculates that it has a chance of success. The group ambushes Sul in the day's race, but Ondai's prediction proves incorrect and Sul easily defeats them all.
Ondai's constant putting-down of living creatures would make one think that he would wish for machines to reign supreme, but this could not be further from the truth; he actually envies organic beings. As a robot, he cannot feel the sensations of touch or warmth, which he longs for. Constant study of living creatures has done nothing, so he hopes that the Ultimate Prize will do that which science cannot; make him flesh and blood, or at least let him feel. His star-racer (in robot mode) was disabled by Prince Aikka in the final race, and he is not seen again, he is presumed destroyed with his star-racer as he isn't seen in the final episode.
- Ondai is one of the characters who first appeared in the 2001 pilot film Molly, Star-Racer.
- In Welcome to Oban, it is revealed that Ondai competed in Sangrar's Pre-Selections after he questioned Satis as to why he was on Oban after being left behind on that planet ("Satis, what in the world are you doing here? We left you on Sangrar, 265.4 lightyears away.").
- Additionally, in the same scene, it is implied that Ondai won Sangrar's first seed to Oban, after commenting on how the Grand Finals' scoring system would work ("81 points maximum, with 112 possibilities of scoring. It's a fair race, but I will still dominate it!").