Kazuhiro Sunseki is a Japanese male voice actor born on April 6 in Aichi Prefecture, Japan. He is affiliated with the talent agency Production Ace. Sunseki is a graduate of the Entertainment Media College's voice actor course and is also a alumnus of the Production Ace Acting Institute.

Sunseki's career in animation began in 2010 with minor roles in the television series Heaven's Lost Property F, where he voiced the characters Mota and Boy C. In the following years, he built a portfolio of supporting and guest characters across a variety of shows. His early credits include roles such as Passerby C in R-15 and several unnamed characters including soldiers, subordinates, and communications officers in the 2013 space opera series Space Battleship Yamato 2199. He also contributed voices to the series Problem Children Are Coming from Another World, Aren't They? in the same year.

Throughout the 2010s, Sunseki continued to take on a wide range of side characters. He voiced Yamada Suisuke in Maken-ki! Two in 2014, a male student in The Testament of Sister New Devil Burst in 2015, and a soldier in The Heroic Legend of Arslan in 2015. His voice work from this period also includes a technician in Active Raid in 2016, a man in the series青春歌舞伎 in 2017, and the character Pokotarou in Recovery of an MMO Junkie in 2017. In 2019, he was cast as Yokoyama Eitarou in Midnight Occult Civil Servants.

In addition to television, Sunseki has provided voices for original video animations (OVAs), web animations, and theatrical films. Notable credits in these formats include the OVA for Recovery of an MMO Junkie in 2017, the web anime OBSOLETE and Onmyōji: Rimbe no Mai in 2019, and the 2021 film adaptation of Farewell, My Dear Cramer. He has also contributed to the Japanese localizations of major video games, voicing the male protagonist in the 2015 title Fallout 4 and the character Rook in Tom Clancy's Rainbow Six Siege, also from 2015. His other game credits include roles in titles such as White Cat Project in 2016 and the digital card game Onmyōji: Hyakki Emaki in 2021.

A significant role in Sunseki's career came in 2021 when he was cast as Baku Yamagishi in the television anime Getter Robo Arc. This series is the final chapter in the Getter Robo Saga, a long-running mecha franchise with a history spanning over 45 years. In the series, Sunseki voices the 22-year-old pilot of the Getter Khan, a power-type robot. His character is described as having an intimidating appearance but a gentle disposition, and he is a skilled hacker and a close friend of the protagonist, Takuma Nagare. Upon being selected for the role, Sunseki publicly expressed his joy at being part of a series he had loved since childhood, while also acknowledging the pressure of inheriting the legacy of the franchise from previous voice actors and living up to the expectations of its long-time fans. His casting in this high-profile project was announced alongside other principal cast members, including Yuma Uchida as the lead.

Sunseki's more recent roles from the 2020s include a school principal and a referee in Farewell, My Dear Cramer, multiple characters in the series Saiyuki Reload: Zeroin in 2022, and the Great Armor-san and Grass Armor-san in the popular anime Chiikawa in 2022 and 2023 respectively.

Beyond his voice acting work, Sunseki holds several professional qualifications, including authorization as a Social Education Director, certification as a Welfare Equipment Consultant, and accreditation as a Certified Health Psychologist. His listed hobbies and skills include performing vocal percussion, playing volleyball, and participating in softball.