Shiori Usami/Plot

Background
Before joining Tamakoma Branch, she was part of Headquarters. Two years before the start of the series, she was the operator of Kazama Squad during its early years. She moved to Tamakoma Branch around a year before the series began.

Black Trigger Retrieval Arc
Shiori first meets them very surprised by there visit. She prepares some sweets for them and explains about the members of Tamakoma Branch. She also explains about the away missions. Then she gives them a tour of Tamakoma Branch and gives them each a room. The next day she explains the roles in Border and then assigns the roles. After Shiori introduces Osamu, Yūma, Chika to Tamakoma Branch. she introduces them to Mikumo, Chika, and Yuma`s mentors. She also helps them decide which position they would take. (Attacker, Gunner, Sniper).

Border Enlistment Arc
When questioned by Yūma as to why he is with Yōtarō, Yōsuke explains that he's babysitting "that little bastard" for her, while Yōtarō tells Yūma that Yōsuke and Shiori are cousins. Yōtarō also explains that Shiori and Kyōsuke were both HQ members until a year ago. Later, she appears at the meeting, aiding Replica in his explanation of the Neighborhood.

Large-Scale Invasion Arc
She is the operator of Tamakoma First during the invasion, giving directions to Karasuma and Osamu so they could reach HQ and battle their opponents.

B-Rank Wars Arc
She acts as the operator of Tamakoma Second. She helps them plan for their battle with Arafune Squad and Suwa Squad.