Cosmo settled on the colony Solo with his parents, and assisted his father Rouri at the Sixth Civilisation excavation site. Along with his friends Deck and Kasha, he was present when the Buff Clan attacked the site. Cosmo took cover in the Sol-Amber truck along with Deck, and soon found himself in the main cockpit of the Ideon robot.
After some early successes with the Ideon, not to mention a lack of any personnel to take over from him, Cosmo found himself as the permanent pilot for the Sol-Amber/Ideo-Delta, and thus de facto pilot of the Ideon itself. He learned his craft quickly, developing into an excellent fighter pilot. This responsibility made him an important figure on the Solo Ship. He often disagreed with the colonists' leader Bes and chief scientist Sheryl over several issues. This probably wasn't helped by the teenager's mood swings, which resulted in a bizarre mix of personality traits - Cosmo was capable of being childish, chauvinistic and disingenuous, or surprisingly mature, caring and insightful. After this clash came to a head and he and Kasha were stripped of piloting duties, he came to see that Bes was acting for the good of all onboard the ship, and developed a good relationship with him, also thawing to Sheryl over a longer period of time. An emotional person, Cosmo was easy to anger, whether flying into a rage after casualties caused by the frequent Buff Clan attacks, or simply berating relief pilot Moera.
Cosmo had a long-running teasing interaction with fellow Ideon pilot Kasha, often mocking her immaturity and, well, gender. However, he cares for her a lot, and develops some sort of romantic feelings towards her. This is never quite acted on, however. Cosmo's true love was Kitty Kitten, a girl on the colony of Kyaral who he formed a brief relationship with before her untimely death at the hands of Daram. This left Cosmo traumatised, though eventually help from his good friend Deck saw him through the worse of it. Like most of the colonists he was initially very suspicious of Karala when she first came onboard, and felt that Bes' feelings for Karala were clouding his judgement. However, in time he came to accept her, and seemed to learn his lesson, being one of the first to support Gije joining the crew.
Cosmo's parents both died on Solo - his father was crushed by falling machinery at the first Sixth Civilisation dig, while his mother was killed when the Buff Clan attacked New Lopia. After a particularly harrowing battle with the Buff Clan left him in shock, Cosmo latched on to the Brazillier base commander Camyula Lanban. Seeing her as a mother figure, he quickly became attached to her, but his death seemed to serve as a watershed, making him fight harder for his fellow colonists.
He is an excellent knife-thrower, able to take out a Buff Clan reconnaissance probe at one point. However, a duel with Gije exposed the limitations of his skill, and Cosmo trained to use a conventional laser sword and pistol. His skills improved, and by the end of the series was capable with both. Cosmo's piloting skills are open to question - while his results are impressive throughout the series both in the Ideo-Delta and the Ideon itself (not to mention a captured Buff Clan Jongu), it is possible that as a young pilot he receives some assistance from the Ideon.
He is killed when the Ideon is destroyed by the Gando Rowa in the final battle between the colonists and the Buff Clan. After this, his spirit is reunited with that of Kitten.
Yes, he does have a ginger afro.