The I-400 class was a series of submarines built by the Imperial Japanese Navy during World War II. These submarines were notable for their large size and unique capability to carry and launch aircraft, specifically the Aichi M6A Seiran. The I-400 class was designed to conduct long-range missions and was equipped with advanced technology for its time. Three submarines were completed in this class: I-400, I-401, and I-402. Each vessel could carry up to three aircraft and was intended for strategic attacks on enemy targets. The I-400 class represented a significant innovation in naval warfare, combining submarine and aircraft capabilities.