Shinji Nishikawa is a Japanese artist, manga creator, and character designer born on October 2, 1964, in Kyoto, Japan. He began his career as a manga artist, making his professional debut in 1988 with the work Dogu Family. Before this debut, while still a student at Doshisha University, he self-published the manga Godzilla Legend in 1986 under the pen name MASH, a name he continues to use occasionally.

Nishikawa is the original creator of the anime television series YAT Anshin! Uchū Ryokō and its sequel, Shin YAT Anshin! Uchū Ryokō, which aired in the mid-to-late 1990s. His other notable original manga works include Silver Haired War and Blue Ocean Mermaid.

While he is widely recognized for his creature design work on tokusatsu films, particularly for the Godzilla franchise starting with Godzilla vs. Biollante in 1989, his role as a manga author and original anime creator is a significant part of his career. He has also illustrated numerous manga adaptations, such as Godzilla: Legend and Monster King Godzilla. In addition to his own creations, his design work has appeared in other notable anime series, including providing creature designs for SSSS.GRIDMAN and its related projects.

Nishikawa's artistic identity is strongly tied to his distinctive monster and mecha designs, a skill he has applied across both his original manga and his commissioned work for major film and television franchises. His industry significance lies in this dual role as both an originator of new properties and a key designer for established ones, bridging the worlds of original manga creation and large-scale special effects production.