Riku is a young man with green eyes and brown hair, residing in Fula City as Risa's younger brother. Confined to the hospital with a leg injury during the Wind Festival, he experiences deep disappointment at missing the event he eagerly awaited. To participate indirectly, Riku persuades his sister Risa to catch an Eevee for him, offering her a pair of red sunglasses as incentive for a task she might otherwise avoid.

Unbeknownst to others, Riku simultaneously acts as the concealed host of the Pokémon Channel throughout the festival, broadcasting updates for those unable to attend. His hidden role is revealed later. When poisonous spores and a spreading forest fire threaten Fula City, Riku uses his broadcast position to remotely assist Risa. As she transports the vital eternal flame to summon Lugia, he contacts her via communication device, providing real-time guidance for a quicker, safer route through the city. Risa questions his knowledge of her precise location, but Riku deflects her inquiry without explanation.

After the crisis, Risa visits Riku in the hospital and presses him again about knowing her location. He once more avoids giving a clear answer, preserving the mystery. Their relationship involves mutual care and playful teasing; Riku understands how to provoke Risa yet deeply values their bond. Despite his hospital confinement, his indirect involvement via the Pokémon Channel and his crucial support for Risa connect him to Fula City's protective efforts.