Hinoki Sai is a key character in the anime series Betterman. She is a brave and determined young woman who pilots the robot Kakuseijin 1 as part of the Akamatsu Industries team. Hinoki is known for her strong sense of duty and her unwavering dedication to protecting humanity from the mysterious and deadly enemies known as Algernon. Throughout the series, she faces numerous challenges and develops a deep bond with her teammates, playing a crucial role in the fight against the looming threat of Algernon.