Shūichi Nishitani is a former Japanese voice actor born on December 25 in Shizuoka Prefecture, Japan. His year of birth has not been publicly revealed, though some sources indicate he was born in 1985. He stands 170 cm tall, has blood type B, and was affiliated with the talent agency Remax. Nishitani graduated from Meiji University with a degree in Theatre Studies and completed the Dwango Creative School program.

Nishitani began his voice acting career in the 2010s, making his debut in 2014 with a role in the television anime The Kindaichi Case Files R. Throughout his career, he was known for supporting performances, often voicing side characters, townspeople, officials, and other background roles across a wide range of anime series. His television anime credits include Food Wars: Shokugeki no Soma, where he voiced staff members and customers; The Heroic Legend of Arslan, appearing as a soldier in multiple episodes; Mobile Suit Gundam: Iron-Blooded Orphans as a Gjallarhorn operator and soldier; The Disastrous Life of Saiki K. as male student and teacher roles; Blend S as a customer and policeman; and Chibi Maruko-chan, in which he voiced famous Japanese singers including Keisuke Kuwata. He also appeared in Active Raid, Knight's & Magic, Hi Score Girl, Sword Art Online Alternative: Gun Gale Online, Sakura Quest, and High School DxD Hero.

In theatrical animation, Nishitani contributed to A Silent Voice as Riku Tanaka, Ride Your Wave as a policeman, The Anthem of the Heart, The Saga of Tanya the Evil Movie as a soldier, and the theatrical version of Aoki Hagane no Arpeggio: Ars Nova DC.

His work extended into video games, where he voiced Ryan in Shin Megami Tensei: Deep Strange Journey and appeared in titles such as Utawarerumono: Mask of Deception and the Yūsei no Shishi series as Saigo Takamori. He was also active in dubbing foreign films and television dramas, providing Japanese voices for productions including Spider-Man: Homecoming, The Amazing Spider-Man, How to Get Away with Murder, and Supergirl. His dubbing work included voicing Carter Hall, also known as Hawkman, and Querl Dox, also known as Brainiac 5, from the Arrowverse. In animation dubbing, he voiced characters in Netflix series such as Danger & Eggs as Phillip and Chuggington as Fletch, as well as in Trolls as Gristle.

Beyond voice acting for screen and games, Nishitani performed in stage plays, including a role in Miyo, Hikouki no Takaku Toberu o. He also contributed to narration for television programs, including NHK's World Documentary, and recorded voice work for commercial advertisements for companies such as Nikon and Takara Tomy. He occasionally performed under the name Ookuma Neko for online and live events.

In early 2020, Nishitani announced on social media that he would retire from voice acting due to increasing discomfort with his speech that had persisted for approximately one year. Despite seeking medical attention, his symptoms worsened, leading him to take an indefinite leave of absence. He officially retired from the industry in March 2020. His retirement announcement was noted for its honesty and transparency with his fans. He remains a former voice actor with no active affiliation following his retirement.