Mahou Shoujo Lyrical Nanoha Vivid - Manga

Four years after StrikerS, the Sixth Mobile Division has disbanded and Nanoha Takamachi has taken a leave of absence to raise her adoptive daughter, Vivio Takamachi. After reaching the fourth grade of her primary school, Vivio is finally given her own device, which gives her the form of the Sankt Kaiser mode. She later meets a girl named Einhart Stratos who, like Vivio, is a descendent of a ruler of the Sankt Kaiser era, and wishes to prove her fighting style the strongest. Together, Vivio, Einhart and their friends enter a martial arts tournament to prove their fighting style the strongest.
from Wikipedia
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Notes

Alternative Names: Magical Girl Lyrical Nanoha ViVid
Author: TSUZUKI Maki
Artist: TSUZUKI Maki
Genre: Action, Comedy, Drama, Ecchi, Fantasy, Science Fiction, Supernatural
Demographic: Shounen
Adapted into the anime, Mahou Shoujo Lyrical Nanoha Vivid