He joined the track club, for he looked up to Shu Kazami, and became the ace of short-distance running. One morning during practice, he and Shu decided to race, but he carelessly tossed the peel of a banana he had for breakfast, and Shu stepped on it, spraining his ankle. He strongly felt guilty about himself, and would shortly after continuously triple whenever he runs on the track, as a disembodied spirit of Shu would grab his ankle. Although Riku could not see the spirit, he could hear him saying “If only I hadn’t stepped on that banana peel”, so believing Shu to be resentful deep down, he tried to endure it, for he did not want Shu to know, believing it would hurt his feelings.
However, when Shu asks Rinne’s help, he had to confess and he learns that he too had created a disembodied of himself, through his guilt, that has been haunting Shu, continuously crying and apologizing, which thus created Shu’s disembodied spirit, filled with regret over stepping on the peel, as he grew tired of dealing with the wailing spirit day and night and stressful from not being able to tell Riku. The two eventually apologize to each other, causing the disembodied spirits of both to vanish.
His last name is written with the kanji for "fast".
He has the same voice of Taro Nekota.