First scenes take many place years ago.
The setting is in Grendan, a colony(city) where the main character Rayphone comes from.
I think it's Rayphone's very first battle after he became a Heaven Sword.
(or a Heaven Sword possessor) It's an honored warrior position in this city.
The other people who are fighting are also Heaven Sword possessors.
The monster they are fighting are called Osenjyu (or Filth Monsters)
They normally eat filth but also take down coloneys for extra calories.
In this scene, the monster is in a matured form. (It seems they change forms like do bugs)
A named monster means something special in Grendan.
It means that the monster was not slain in a previous attempt, and has come back to attack again,
thus was given a name in the previous attempt.
I'm not sure of its name sorry.
The horrified guy is the student council president who comes up later.
He sees Rayphone here for the first time and is astonished by him.
In the next scene, Rayphone is departing from Grendan. This is the present time.
He was discharged as a Heaven Sword for dishonorable conduct, and only his childhood friend supports him.
Rayphone is now heading for Zerni, another city (colony)
Next scene, in the 17th platoon training room.
The cities try to kill each other off, for stuff like resources. So as a military unit they have platoons.
Inside the city they have inter-platoon matches. There's also the inter-city matches, which are war lol.
The academy here at Zerni has two departments which are general study and martial/military arts.
Those who are in the military arts are able to use the 'Kei' to fight.
Rayphone chooses to enter the general studies dept, after he was dishonorably discharged,
and tries to distance himself away from martial arts.
Restoration is what people keep on shouting when they make their weapons appear.
It seems by letting kei flow into their dites their weapons take form.
Cities or colonies are mechanical stuff. They need resorces to keep their legs moving.
That resource is called Serenium(or something). Without them, a city can not survive.
Those are mined out of mines, and inter-city battles are fought for mines.
Because these cities are mechanical, it has a machinery section inside to move its legs.
Rayphone will work part time here as a cleaner, and Nina also has been working here.
