Mari Akane - Artian's best female friend. In later episodes, she dosen't appear too often.
Dewey Kito - Rohan's best friend. Introduced somewhere into the series. Dewey has just about as much energy as Rohan. He also stands by him when the times get tough. As of series 2, he and Rohan are now friends with Suba Kushyu, who used to be Rohan's rival.
Rini Kito - She is the older sister of Dewey Kito. In an episode in the last part of Series 1, Dewey reffers to her as "Weenie" in the English dub. She seems to get on great with Artian Kuino.
Kirsten Kebu - Rohan's best friend and cousin. She is the older sister of Wataru and the cousin of Rohan as of season 3. She is the blonde-haired girl who lives next door to Rohan. They are friends (mainly because their parents are friends) but sometimes they don't like each other. In later episodes, they grow apart, and she is seen less in Series 2, more or less than her little brother. She and Rohan are polar opposites. Rohan is imaginative and energetic. Kirsten is analytical, literal, and hardly ever gets excited. She can be seen as a Temari type
Wataru Kebu - Rohan's younger cousin, he often gets on the nerves of the older kids. As of Series 2, he is 11 years old
Sabrina Haruki (called Sakura in the Japanese version)
Yori Mizuna - The first potential love intrest for Rohan. She is shy. She and Rohan often fall for each other, but not simultaneously.
Dani Yungo - She is a tomboyish girl who was always seen bickering with Rohan, whom she secretly likes. But they seem to get closer as of series 2. It is made known that she has a younger sister at the end of series 1. A potential love intrest for Rohan. At first she's mean to Rohan, but starts being nicer to him later on.
Subaru "Suba" Kushyu - He was introduced as a rival for Rohan. But then towards the end of the series, he says he wishes he was more like him, as he had envied Rohan, due to the pressure Suba's parents put on him constantly. He appears as a more friendly rival in series 2.