Gun Dragon Sigma

In the year 2030, the secrets of the universe has been unraveled and visitors from various planets have appeared on Earth. In order to avoid sudden contact with other world civilizations, the Earth Alliance limited the area of trade and built a huge populated island called "Dejima" in the southern part of Okinawa, Japan, bordering Taiwan. The aliens are prohibited from stopping at ports other than Dejima, but various crimes began to occur frequently on Dejima, where different civilizations and values were mixed. In order to protect the security of the area, the Dejima Police of the Earth Alliance, the Federation Police of the Space Alliance, and a mixed force of aliens and earthlings were established. This was the "Gundragon". Gundragon's investigator, Sigma, stopped a runaway truck carrying smugglers. On the back of the truck, a Mumerian from a water planet, who commits suicide to protect its secret. Sigma sneaks into a tavern in search of his friends, where he finds a Mumerian and a small black hole, which is forbidden by the United Space Federation...

(Source: Art Technika, translated)