The Hakone Incident, also known as the Sankai Resort Incident or the Battle of Hakone was an international incident resulting from a four-way engagement between the Japan Self-Defense Forces, US CIA Special Operations Group, The Russian CPB, and the Chinese MSS. The latter three forces intended to capture the visitors from the Special Region who were housed at the Sankai Resort in Hakone, Japan, in order to gain intelligence about the region.
Due to faulty intelligence from the higher-up, the initial engagement occurred between the Japanese Self Defense Force Special Activities Division forces and the CIA Special Forces caused at least a few members of each unit were killed. Furthermore, due to Japan strict border control policy, most of CIA members are under-equipped forcing them to smuggle weapons and purchased military support hardware from local civilian tourist shop making them lack the advantage to deal with JSDF Special Force effectively plus some of the CIA members arrogantly forgot about the fact that the JSDF Special Force used to received training from US Special Force in the past, which makes the JSDF Special Force as good as CIA. However, the JSDF forces were ordered to retreat after the CIA blackmailed Japanese Prime Minister Hino into removing the JSDF guards with threats of releasing evidence of corruption. With the JSDF guards removed, the US, Russian, and Chinese special forces encountered each other, leading to a chaotic three-way firefight. Rory Mercury, then staying in the hotel with the Third Recon Team and the other visitors from the Special Region, armed herself with her halberd and joined the fray, causing further casualties but she . Between the firefight and Rory's intervention, the few still living foreign Special forces were forced to retreat.
In order to avoid a scandal of the recently revealed corruption, Hino resigned shortly before news of the scandal reach public exposure.
The Third Recon Team seized weapons from the fallen agents and escaped along with the visitors to the region, along with Risa; notably, Piña, with the help of Bozes, tried a scheme by smuggling a couple of guns to present to her father, but this failed later as the princess was ignorant of modern metal detectors. As the envoy was set to return to the Special Region, all three foreign special forces plot a second attack in an attempt to capture the envoy with the CIA planning to blind Rory using smoke and incapacitate her. The attempt failed when they realized a blog post by Risa was shared throughout the internet and attracted thousands of civilian witnesses intent on seeing the visitor from beyond the Gate as they returned.
The large number witnesses and sheer chaos within the crowd made covert actions impossible, and the Special Region envoy returned without incident. Shortly afterwards, all three foreign powers ordered their covert agencies out of Japan and denied any responsibility for the incident.