Ryuji Amagai is the Japanese captain of the Kakegawa High School soccer team. His surname, Amagai, combines the kanji for "rain" (雨) and "valley" (谷). His given name, Ryuji, meaning "noble, prosperous" (隆) and "two" (二), follows the convention for a prosperous second son. He serves as a supporting character within the soccer-themed narrative.