Shin Ikushima is the main protagonist of the Sentoki series, He is a martial artist hailing from Okinawa, Japan. One day, Shin witnessed the death of his mother Shiho in the hands of Orion's soldiers, and has since swore to avenge her death, putting himself through years of rigorus training in order to achieve the strength he needed. Upon finding out about the Sentoki tournament, Shin decides to enter it in order to seek vengeance for his mother.