The movie is not a sequel to the anime, but is an adaptation of all the events in the first novel and contains events that were not in the anime series. 
(Source: Wikipedia)

Various scenes from the movie represented with a very tiny Shana and distorted bits of the story.

A promotional short special for the movie where Shana and Yuji explain different terms from the show.

He had thought his normal days would last forever, until they were ended abruptly by an encounter with a girl with red hair and eyes. He named her Shana. 
Not long after he enters high school, Sakai Yuji&rsquo;s normal days come to an end. He sees something bizarre on his way home: people are frozen in a strange fire, and a monster that looks like a large doll is attacking them. Just when he's about to be killed, a girl in a dark cloak wielding a large sword appears, and slices the monster in half. Although Yuji survives the strange encounter, the girl informs him of a desolate truth: " 'You' don't exist anymore." 
She calls herself a Flame Haze who hunts "Guze no Tomogara"; intruders from another world. She explains to him that he is a "Torch", a substitute of Yuji whose &ldquo;existence&rdquo; has already been devoured. She also told him that he is a special Torch, "Mystes", which contains a precious item in it. When he looks at his chest, he sees within himself a faint flame, just as she said. 
It is in this way that his eternal struggle alongside the girl begins. 
(Source: AnimeNfo)

Invaders from the Crimson Realm have descended upon Earth looking for something called the Power of Existence. Whoever possesses this power will control the very fabric of existence. To the rescue comes an otherworldly young girl with fire in her eyes. She may be cute and petite, but she's endowed with enough preternatural strength to save the entire universe. Plus, she's got a really big sword!
 
(Source: Viz Media)

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