She is a black ops operative who happens to be Yuuji's guardian and handler. Her former name is Julia Bardera but she changed it after moving to Japan, that’s why Yuuji calls her JB. Though she looks American, she is a mixed blood between German and Italian.

The anime revolves around Mihama Academy, a prison-like school built to preserve fruit that has fallen too far from its tree. It is home to five female students who each have their reasons for enrolling in the academy and live their life idly within the walls of Mihama. 
 
One day, Kazami Yuuji the institute’s first male student arrives and throws the orderly rhythm of Mihama off balance. Is Yuuji what the girls need to hold of their lives once more, or will the weight of their pasts prove too steep a wall to overcome? Or is his past even heavier than any of the others? 
 
(Source: Crunchyroll)

The Grisaia no Rakuen visual novel continues the Grisaia no Meikyuu visual novel's main route and concludes the trilogy. It also includes a prologue following the five heroines as they arrive at Mihama Academy.

The Grisaia no Meikyuu visual novel is a collection of sequels for all of the game's heroines, and also includes a prequel story for the hero and dozens of short stories. The first episode will be a 60 minute special that will air at the end of march.
 
Having attended Mihama Academy for about a year, Yuuji Kazami has seemingly found his place within the school, but he suddenly decides to pursue a promotion in CIRS. After consulting JB about his intentions, they both thoroughly examine Yuuji's documents and dissect the events of his upbringing to determine if the job is fit for him.
 
Meanwhile, unbeknownst to the two, the girls of Mihama uncover some torn documents in Yuuji's room. After restoring the papers, they discover the story that has formed—or perhaps broken—Yuuji into the man he is today. However, what was thought to be history has haunted him to the present, and the chains of the past begin to drag him back into the darkness...

Short specials included in the Blu-ray and DVD releases.

Yuria Harudera