Year 1937, the world experienced a strange phenomena that completely changed the course of humankind. The bright, blue sky was slowly black and when the darkness completely enveloped the entire above, countless portals appeared. All people panicked and didn't know what to do when suddenly, they collapsed and experienced a comatose for one week.

     It was a common knowledge that those who lived that time possessed an unknown skill that they later called "vessel". They were given the ability to materialize a soul of a person from another world that died and wished for second life. They were called "master" and these apparitions were referred as "spirits". Except for being revived in the new found home, "spirits" were given the Earth's basic knowledge like knowing human language.

     At first, this relationship between "master" and "spirit" called "spiritual pair" was seen as a threat by the leaders of each nation because the "spirits" came from fantasy worlds and were carrying weapons like swords, scythes, and lances. If there is a common denominator to them, it would be the manifestation of only one ability. One of the condition of being revived is to only carry a single skill they possessed to preserve the Earth's harmony.

     Most of spirits only asked for second life and are now living like they're residents of Earth but there are still some spirits that wants to create havoc and to even do world domination. Due to this countless incidents, the elite organization known as "Enforcers" were created. The group was composed of the strongest spiritual pairs for them to suppress those who disrupt peace that were called "Destroyers". Because of the astonishing efforts of the "Enforcers", the crime rates was immediately dropped from 20% to 1% within two weeks.

     Months after the phenomenon, an universal law was created for mortals and spirits to coexist freely. Both agreed on the terms and conditions.

     Based on the internet, the world's economy started to rise in the year 1939, when the spirits lended their hands on building the very foundation of new humanity. Trades and treaties between nations became more persistent that caused the civil alliance between countries to become more important and stable. This leads to creation of facilities that was way too beyond human comprehension. The humanity's zenith was reached in the year 1945.

     Masters that were under 18 years old gradually increases in numbers. This is the reason behind constructions of academies intended for spiritual pairs. The most advanced academy built was the Pacific Academy.

     It was divided into four branches, the Pacific First up to Pacific Fourth, each was located on Pacific Ocean that was based on primary directions. There is a rumor that 70% of the graduates here each year were being qualified to become a part of "Enforcers". It just shows that the academy's methods were exquisite.

     The arrival of "spirits" totally altered all aspects of our lives. Now, year 2037, the world is facing the its new history that no one anticipated but all wished for it. We're now in "Post-spirit Era".