Shun Nitta debuted as a forward for Otomo Middle School, emerging as the primary rival to Tsubasa Ozora's Nankatsu team during national tournament regional qualifiers. He propelled Otomo to victory in the Shizuoka prefecture tournament after Tsubasa's departure, showcasing exceptional speed with an 11-second 100-meter sprint. His signature Peregrine Falcon Shot evolved mid-match into the No Trap Running Volley Peregrine Falcon Shot to counter Tsubasa's marking in the Otomo-Nankatsu final. Overcoming initial technical struggles and crowd mockery, he mastered the volley within 30 minutes to score an equalizer, though Nankatsu prevailed 3-1. This highlighted his resilience and rapid growth under pressure. Selected for Japan's Junior Youth team as an injury replacement for Tsubasa, he became a starting forward despite being a year younger than peers. His speed remained pivotal, clocking 50 meters in six seconds internationally. However, elite goalkeepers like Genzo Wakabayashi and Hermann Müller frequently saved his Peregrine Falcon Shot. Coach Gamo excluded him from the World Youth training camp for lacking ambidexterity. Through rigorous left-foot training with weights and tire-kicking drills, he returned unannounced to score a left-footed Jumping Peregrine Falcon Volley against RJ7 goalkeeper Yamada, securing his national team reinstatement. Post-youth, he enrolled at Nankatsu High School, reuniting with former Otomo teammates under Taro Misaki's leadership. He turned professional with J.League club Kashiwa Reysol (jersey 35). During a São Paulo stint in Brazil, he thrived under coach João, mastering Artistic Dribble and netting hat-tricks in five consecutive matches. Temporary refusal to join the national team sparked naturalization rumors, but he transferred to Campione—a squad that defeated AC Milan without its stars. His arsenal expanded to include the Falcon Claw shot and collaborative Shadow Strike with teammate Alcion. Later, he joined Borussia Dortmund in the "NEXT DREAM" arc, leveraging refined speed and techniques like the Non-Trap Running Volley Falcon Shot to breach defenses. He maintained his role as Japan's secondary forward behind Kojiro Hyuga across U-23 and senior levels, wearing jersey 18 internationally. Physical attributes include 172 cm height, 60 kg weight in his prime, dark brown shoulder-length hair, and a distinctive fang.