The Byttin School of Mechanics is perched on a cliff near the sea, surrounded by blue cornflower bushes that bloom all over the hillside. The architectural style of the school building retains the elegance and luxury of the old European style, and it looks like an old church used to convey God's will.

The complex of buildings revolves around a central auditorium, which is symmetrical to each other in the form of flowers. The central auditorium is known as the "Hall of the Purple Roses", and it gets its name from the eight purple rose windows inside it. The rose windows are a rare remnant of the old era, unlike the marble statues that stand in the courtyard, which escaped the unreachable height when the demons attacked.

In addition, the most popular of the Purple Rose Hall is the four corridors supported by pointed ribbed vaults. This bizarre form of vault resembles the tall hat worn by popes in old days, and the rounded spire gives the impression of a wide and tall space. The dome is divided into small squares by cross-shaped lines, painted in different but bright colors, like the sky of Eden in a picture book.

This style of architecture was called "Gothic" in the old era, whether it is the rose windows or the vaulted corridor domes, those brilliant colors give a strong impact of perspective, but the sharp towers and intricate carved columns of the architecture give people a sense of oppression and darkness.

Fortunately, there is a group of young children who often pass through the corridors with laughter, girls discussing the flowering of cornflowers, and boys discussing the fluttering skirts of girls. A gentle breeze swept through the corridor, and the fragrance of flowers filled the air, covering the not-so-pleasant smell of lube, the smell of rough steam.

There is an open-air plaza to the west of the Purple Rose Hall, and large loading machines are set up next to the huge stone flower beds around the square. Graduating students gather around the plaza, where the final mech control exam will be held.

"Now I'm going to announce the assessment rules," Professor Uno stood on the edge of the boulder flower bed and waved his hand to call all the students, he is the professional director of the mechanical design and operation major, and also the examiner of this final assessment, "Due to the limited school furniture mecha in the school, the graduate assessment can only come in twos and twos, you can be free to divide into groups, but once you fill out the registration form, you can't change it." ”

"The rules are simple, the number of points scored is recorded based on the intensity and number of hits to the opponent's vital points. The winner gets an additional bonus to the number of points, and there are three conditions for winning: the opponent can't get up again; Knock the other party out of the assessment venue; The other party took the initiative to admit defeat. The weapon used in the assessment is an unbladed knight's sword, so don't hurt the opposing driver, otherwise it will be dealt with in violation of the law. ”

The students voluntarily divided into two teams, lined up on either side of the registration desk, and most of them took the initiative to form a group with their teammates who were good to each other, so that during the match, both sides would deliberately give up the opportunity to hit the opposite side, so that they could both get similar high scores at the end of the game. The academy does not prohibit this practice, the main focus of the combat assessment is the operation of the machine, not the skill of combat, and they do not want to see anyone injured by the exam, after all, when these students graduate and join the Guardian Army, their enemy will be demons, not their companions.

When the students were grouped and the teachers had counted the numbers, Professor Uno nodded and motioned for the assistants to get to work. Several men in white overalls ran up to the massive loading machine, and together they ripped off the dark covering cloth that covered it, finally exposing the mighty metal figure beneath it to the sunlight.

The students cheered, it was two school mechs.

In fact, a large number of people here are still seeing this kind of mecha for the first time, and they usually practice in the suspended cockpit. The real steam mecha is just a picture in a book for them, and when they stand in front of such a great machine for the first time, they will naturally emit admiration from the bottom of their hearts.

Steam mechs, also known as Iron Knights, are mysterious machines that have existed since the old times. According to legend, more than 300 years ago, when Byttin was still a city-state, the most popular thing in the city at that time was ancient magic called "witchcraft", and the most popular thing in the city at that time was wizards. The lord of the castle, Sievers Atio, was also a famous wizard, and he was close to the Wizards' Guild at the time, marrying his only daughter, Tess Atio, to Dolphman Igny, one of the most powerful wizards in the Society.

After Sipfers' death, Tess succeeded him as lord of the city, and the city-state of Byttin grew under her, eventually establishing the kingdom of Bytin, herself becoming the first monarch of the kingdom. As a result, female monarchs became popular in the kingdom, which lasted for more than 300 years.

But strangely, Her Majesty is not fond of witchcraft, and she does not possess the ability to use magic at all. Unlike her father and husband, who were great wizards, she was passionate about steam and machines. She had a unique insight into the design and manufacture of machinery, and she led the people of the kingdom to build machine factories and invent new steam engines, which for a time made Betin the most developed steam kingdom in Europe.

The design of the coat of arms of the Bytin Kingdom is also based on the "Land of Steam and Witchcraft", with a circular metal gear in the center, which represents steam and machinery, and a red full moon representing witchcraft in the center, surrounded by a pattern of waves, indicating that the Bytin Kingdom is a kingdom by the sea.

It is said that the kingdom's first steam mecha was created by Her Majesty Queen Tess, and at that time, this god-like machine could only be regarded as the ultimate secret weapon, with extremely high production costs and no great use value, and it was simply a live target in front of machine guns and cannons. Therefore, it is said that the Queen's design was sealed in the treasury from the first day it was manufactured, and it was covered with the dust of history.

Until that day eight years ago, the demon descended, the kingdom's power system was destroyed in all directions, and the living area of human beings was extremely reduced. With the complete collapse of the royal power and the rise of the chaebols, the steam machine came to prominence after many battles with the demons, and the design that was sealed in the depths of the treasury was made public, and eventually became the main weapon against the demons.

However, the number of mecha formations in the Guardian Army has always fluctuated drastically, not because the chaebols can't build more steam mechas, but because there are very few people who are really suitable for piloting mechs. According to Her Majesty's design, the entire control system of the mech is fully connected to the pilot's consciousness system, and is communicated with each other by a connecting fluid known as the LCL. However, this design is a great test of the driver's own mental tolerance.

The synchronization rate between a normal person and a mecha can only reach about 20%, and to become a qualified pilot, the synchronization rate must exceed 40%. The 40% figure is called the "chosen number", and those who reach this number are often referred to as the "chosen ones."