Douglas Billingham, known as Doug, is one of the main protagonists in the anime series Double Decker! Doug & Kirill. He is a seasoned detective working for SEVEN-O, a special investigation unit tasked with tackling the dangerous drug 'Anthem.' Doug is known for his sharp intellect, unorthodox investigative methods, and calm demeanor. As Kirill's experienced partner, Doug acts as both a mentor and a mysterious figure, often hiding his true thoughts while guiding Kirill through complex cases and dangerous encounters.