EVA-04 is the fourth Evangelion unit introduced in the anime series Shin Seiki Evangelion (Neon Genesis Evangelion). Constructed in the United States, EVA-04 was intended to further the research and development of Evangelion technology. However, during testing with the experimental S² Engine, the unit and the entire NERV Second Branch facility disappeared in a mysterious explosion. EVA-04 never appears in active combat within the series and serves as a symbol of the dangers and unpredictability of Evangelion experimentation.