Nagare Tatsumi

Male. Go Blue. 23 years old, the second eldest. A firefighter. He has a cool and calm personality and is the smartest among the five. When conducting research or building equipment, he pours all his focus into his work in his room for long periods. His habit while researching is tying his hair back. The Go Blaster, a piece of equipment used in the latter half of the series, is his invention. While usually composed, he can become uncontrollable if he loses his temper.

Sho Tatsumi

Male. Go Green. 22 years old, the third eldest. A rescue helicopter pilot. A sarcastic and cynical rebel. Surprisingly, he is shy and weak around women. Despite his rebellious streak and tendency to stir up conflict, he is deeply affectionate and is the first to step up when someone is hurt, suggesting a tsundere nature.

Daimon Tatsumi

Male. Go Yellow. 21 years old, the fourth eldest. A police officer. He has a childish and comedic side, loves milk, and is a master of martial arts. He is a purely kind-hearted person.

Matsuri Tatsumi

Female. Go Pink. 20 years old, the youngest. An emergency medical technician. Though she is the youngest, she doesn't act like it, often showing a mature, sisterly side. However, she was quite a crybaby as a child and grew up being protected by her four older brothers.

Mondo Tatsumi

The father of the Tatsumi siblings and the head of the Tatsumi Disaster Prevention Institute. His talent is truly remarkable, having been called a child prodigy. In 1986, he predicted a great catastrophe brought by negative energy from space and left his family to independently develop the mecha and equipment for GoGoFive. Although he did it for the future of the Earth, he disappeared for 10 years without a word to his family, and his occasional clumsiness and airheadedness lead his children to find him somewhat unreliable.