One of Lutecia&#039;s many insect summons. Unlike the others his size is closest to a human. Acting as a counterpart to Erio as Lutecia does to Caro, Garyuu is the most intelligent of Lutecia&#039;s summons and the only one capable of thinking independently in order to protect her even against her commands. Garyuu&#039;s elbows and forearms sheathe blade-like growths - when Lutecia went berserk, Garyuu further grew a pair of tendrils from his shoulders and a trio of metallic, blood-soaked blades from his forearms. This alternate mode also caused him to cry tears of blood - Caro remarked that Lutecia was hurting Garyuu by forcing him into this boosted form. He also possesses the ability to camouflage himself and is superior to Erio in aerial mobility.    -Wikipedia-

Chapters 1-3 are the events that occurred between the end of A's and the start of StrikerS. 
Chapters 4-12 are side stories about the characters. 
Chapters 13 &amp; 14 are the events that occurred after the end of StrikerS. 
Chapter 15 is a special from Megami September 2009 (also events after the end of StrikerS).

The series takes place four years after the events of Mahou Shoujo Lyrical Nanoha StrikerS, during which Nanoha Takamachi rescued and adopted a young girl named Vivio, who is the reincarnation of the Sankt Kaiser, Olivie Segbrecht. After entering her fourth year of elementary school, Vivio is given her own intelligence device, Sacred Heart, and gains the power to transform using her adult Sankt Kaiser mode. She soon comes across a girl named Einhart Stratos who, similar to Vivio, is the descendant of another Sankt Kaiser ruler, Claus G.S. Ingvalt. As Einhart becomes determined to prove her fighting style is the strongest, Vivio befriends her and, together with her friends, enters a martial arts tournament where they fight against various opponents and learn more about their past lives.
 
Included one-shot: 
Volume 2: 5th Anniversary Collaboration Comic: Fate/stay night x Mahou Shoujo Lyrical Nanoha

The manga takes place four years after the JS incident in Magical Girl Lyrical Nanoha StrikerS, and stars Vivio Takamichi, a fourth-year elementary student at St. Hilde Academy of Magic. Vivio has learned to conjure her adult form and has received her own Device — named Sacred Heart — from Nanoha, and has promised Nanoha to never use either for mischief. Then a mysterious magical fighter appears and targets Vivio.
 
(Source: Anime News Network)