Ok, I would take inspiration is anime itself.
I'll start with the Main character. Toumura Uzunaki a 16 yearold ninja wizard with a heart of gold and a habit of spreading light everywhere he travels. He lives in the countryside with his master, Tama-sama. Tama-Sama is the spirit of a dog and the only one capable of teaching Tomura the ways of the ninja wizard before the dark lords evil world domination plan is put into action.
The 1st episode will take place on the morning of Tomura's 16th birthday, he'll wake up to find a masked monster finishing off killing Tama-Sama. *dramatic scream* "How dare you kill my master, that is unforgivable". After Killing Tama-Sama thr monster bursts into flames, this we find out later on is a special technique which allows the evil monster to seal it's self away deep within Tomura's soul without him noticing.
After breaking down and swearing revenge on the monster Tomura notices a piece of paper on the table in the kitchen, it's a high school acceptance letter for a high class private school in Tokyo.
After mulling it over he decides to quit his life as a ninja wizard and trade it for a "normal" high school life. He arrives at his schools dorm only to find his childhood friend Misuki cleaning the hallway. Misuki has always loved Tomura since the day he found her naked in the forest, nursed her back to health and helped send her of to school in Tokyo. Unfortunately for her whenever she feels herself getting close to anyone she can't help but act cold and sometimes lash out at that person. Misuki is also an alien, this isn;t really important but it explains why she was naked in the middle of the forest that one time.
The day of his introduction as the new transfer student arrives, the class are excited as it's rare for a transfer student to transfer in so late into the year. He introduces himself in the usual way and takes his seat (3 from the front 1 from the back). From the window he he catches glimpse of a what looks like a girl being mugged by a a gang of generic delinquents. He opens the window, jumps out and runs over to the girls aid. Without breaking a sweat takes out the delinquents but this isn't the end of this. The surrounding area turns blue and everyone but him and the girl he just saved are frozen solid.
"HAHAHAHAHAHAHA I am Erza of the dark zone and me and my companions have enrolled in this school to take you down". Erza, using the delinquents to lure out Toumura demands a fight but he refuses to fight a girl. She beats him senseless with a selection of magical abilities for a good half an episode, she's a bout to land the final blow when from somewhere the words "it can't be helped" are muttered. A sudden burst of energy radiates from Tomura, the energy around his body takes the shape of the monster that killed Tama-Sama and he starts to attack Erza. The fight lasts a matter of seconds but get this, once the fight ends she falls in love with Tomura.
In the next scene Tomura is in a dream like state (in his soul), he meets the monster that killed his master, the monster reveals that the master was actually a member of the dark zone. He is told the truths that he was only being taught the bare minimum to make it look like training but really he was just being kept an eye on by the dark zone. The monster also reveals some facts about it's self. It can grant amazing strength to him but every time he relies on the darkness strength it moves one step closer to consuming him
He wakes up in the nurses office with Misuki and Erza looking after him. He notices a strange tension between the two girls but cant for the life of him figure out what's going on.
Over the next few weeks fierce battles continue. After each battle new girls (and a reverse trap) are added to Tomura's harem.
A day after the 11th battle the final boss appears. Tomura takes a look at it an you wouldn't believe what he sees.....It's his former master and a small platoon of 12 evil looking but hot magician girls. "how could this be, the monster that is inside me killed you"
"How can you kill a spirit, i was right to raise you stupid"
Tomura accepts it and prepares his battle harem for war.
Lots of laser spam later the dark army have been defeated, the only enemy left on the school field is Tama-Sama. Tama transforms into a giant savage devil wolf and Tomura follows suit, using the monsters power he defeats his former master for the safety of the world.
But it's not over yet, Just as the evil falls the monster within totally takes control of him. His battle harem try to restrain him but fail miserably. Many of the girls die by the monsters fierce claws but they keep trying.
Out of nowhere a bright soothing light starts to come from every pour of alien harem member Misuki. The battlefield now bathed in light and the monster loses it's will to fight. Tomura's body is returned to him and the fallen harem members return to life (even if most of their clothes have now been destroyed).
It is later told that Misuki's mysterious power drained most of her life energy away and it is implied she will die in the near future.
He doesn't definitely pick a girl but it's implied that he picks Misuki. He promises that he will travel to her home planet to find the magic gummo gummo fruit which will return her life energy. Those events take place in season 2.
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Just call me Lapraso Miyazaki.
