two years ago
Eighteen years after the presence of Thanatos was first detected, the giant space dragon realised she had released her eggs on a planet that wasn't actually uninhabited (as she'd originally thought). Deciding that humans were unfit for her offspring to Resonate with, Thanatos decided to cut her losses by sending three "probe" dragons to Earth in order to guide her wayward offspring home. These "probe" dragons were given great strength but limited life spans for their brief mission (they were disposable road signs, essentially).
Unfortunately things did not go as Thanatos had planned - at the same time as the dragons were entering Earth's atmosphere, ISDA Flight 29 was leaving the atmosphere. The dragons collided with the Moon-bound civilian shuttle. All humans on board the flight were killed except for Kamishina Jin (the pilot's son) while the dragons were injured to varying degrees.
As information about Thanatos and its dragons had been suppressed by the ISDA, the general public remained unaware of the alien involvement in the crash. All the blame for the accident was subsequently placed on the dead pilot. Jin, as the sole survivor, suffered greatly at the hands of others who felt his father was responsible for the tragedy. There was also confusion as to how Jin managed to survive the accident that had killed his family and so many others.
Although unaware of it at the time, Jin was rescued by one of the dragons that had collided with ISDA Flight 29. Dubbed "Album" by the ISDA, this white dragon Resonated with Jin during the accident and rescued him before he could fall to his death. Jin's memories of this time are hazy at best and he has no recollection of the dragon's human form ("Toa"), which becomes apparent when they meet again two years later. The ISDA however, is aware of Jin having performed a Resonance though they cannot identify the specific dragon.
Immediately after the shuttle accident, the ISDA sent out several researchers to retrieve pieces of the craft and other evidence that had been scattered over the various islands near the crash scene. Kitajima was one such researcher and during her investigation, she found a severely injured dragon (dubbed "Atrum") that had been involved in the crash. After she touched the creature it disappeared, leaving her alone. Like Jin, Kitajima performed a Resonance with one of the "probe" dragons though she too was unaware of it at the time. When Kitajima attends the memorial held for the victims of the shuttle accident, she is observed by Atrum (whose brush with the scientist has left him with both human form and feelings). Overflowing with guilt, as well as the desire to protect both the eggs he was sent to retrieve and the human with whom he'd performed a Resonance, Atrum became "Nozaki Kasuga" and began work with the ISDA.
Sakaki Baisil, the ISDA's military commander also searched for evidence after the shuttle crash (despite losing his wife and daughter to the accident). He came across the third dragon involved ("Ravum") and inadvertently Resonated with it. This dragon manifested itself as his dead child ("Laura") but the Resonance process somehow robbed her of the ability to shift between human and dragon form. Ravum's corpse-like shell was stored in the ISDA's science facilities while Sakaki hid "Laura" with him.
Once everyone at the ISDA had recovered from the shock of the accident, the research into using dragons as potential weapons against Thanatos began to take shape. The project was centered around creating a team of "Dragonauts" (humans who could use Earth-born dragon partners as weapons in battle). Kitajima (along with her new superior, Nozaki Kasuga) worked on the scientific end of this plan while Sakaki oversaw the military element.
Outside of the ISDA's walls, a lonely Kamishina Jin was taken in by relatives and resumed attending school.