Nicola Koga is a member of the Rainy Cocoa Fan Club and the younger twin brother of Noel Koga. He is also the younger brother of Shion Koga, the manager of the Rainy Color café. Nicola comes from England, where the Koga brothers originally lived before joining their sibling in Japan and later travelling to Hawaii. He has dusky light brown hair and forest green eyes, and he typically wears a loose daffodil yellow jumper with a V-neck over a white collared shirt. In contrast to his twin brother Noel, who is curious and energetic, Nicola is shy, cautious, and conservative. He shares with Noel a deep admiration for their older brother Shion, often described as having a brother complex. Nicola is motivated by a desire to support Shion and to be part of the café's activities. In the story, he and Noel travel to Hawaii to help at the new Rainy Color Waikiki location, where they assist with store preparations, develop new menu items such as pancakes, and take part in local celebrations like Halloween. Although he is initially reserved, Nicola gradually becomes more involved in the day-to-day workings of the café. He does not display any supernatural or extraordinary abilities; his contributions are those of a helpful and loyal sibling who prefers to stay in the background.