Seizō Watase(わたせ せいぞう or 渡瀬 政造Watase Seizō) is a Japanese manga artist and illustrator born 15 February 1945 in Kobe, Hyōgo Prefecture, Japan. Outside of being an illustrator for numerous posters, books, and other works, he is most well known for his dramatic romance manga Heart Cocktail, which had sold over 5 million copies as of 1998. He won the 1974 Shogakukan Big Comic Prize. In 1987, Watase received the Bungeishunjū Manga Award for his work Phillip, P.I.(私立探偵フィリップShiritsu Tantei Firippu).