Seizou Watase is a Japanese manga artist and illustrator born on February 15, 1945, in Kobe, Hyogo Prefecture. His early years were spent in Kitakyushu, Fukuoka Prefecture, before he eventually graduated from Waseda University with a degree in law. Prior to establishing himself as a full-time creator, Watase worked for over sixteen years at Dowa Fire and Marine Insurance Company, a career he left in 1985 to focus entirely on his artistic work.

Watase is most widely recognized for his long-running manga series Heart Cocktail, which began serialization in Kodansha’s Weekly Morning magazine in 1983. The series, a collection of short, dramatic romance stories, ran for six years and became a significant commercial success, selling over five million copies. It is considered the representative work of his career. His other notable manga include Chalk-Iro no People, a work that also received an anime adaptation, and Phillip, P.I., for which he received the Bungeishunjū Manga Award in 1987. Earlier in his career, he had already won the Shogakukan Big Comic Prize in 1974.

Several of his original manga works have been adapted into animated formats. The most prominent is Heart Cocktail, which was adapted into a television anime series that aired on NTV from October 1986 to March 1988. The series was notable for its collaboration with jazz and fusion musician Naoya Matsuoka. Heart Cocktail was also later adapted into an original video animation titled Heart Cocktail Again in 2003. As noted in the provided examples, his manga Chalk-Iro no People was adapted into an OVA in 1988. Additionally, he contributed image design for the 1985 anime film Bobby ni Kubittake.

His artistic identity is strongly associated with a particular aesthetic that blends a wistful, romantic sensibility with a focus on adult relationships and slice-of-life narratives. Critical reviews of his animated works, such as Chalk-Iro no People, describe a style that is minimalist and atmospheric, prioritizing a bittersweet, haiku-like mood over complex plots or technical animation flourishes. His work often evokes a sense of nostalgic romanticism, frequently complemented by the use of jazz and other sophisticated musical scores. Beyond manga, he has maintained a prolific career as an illustrator for posters, books, and advertising, and his work has been featured in exhibitions, including a major one in the United States in 1998. His creative output has continued for decades, with new projects such as the manga Natsuno no Kyō launching as recently as 2020.