Byakkou

Shironiji is a Summoner and she participates in Operation Capture as a member of the Akiba Raid Party.

In real life, her name is Rakusu Amamiya (雨宮らくす Amamiya Rakusu).

Prior to the Catastrophe
Shironiji has an older brother named Yoriyoshi.

Fallen Guardian arc
She appears in the Akiba Raid Party training grouds, bringing Seine with her, and she asks if they could participate.

She tags along Mikakage in Team F, where she summons a Golem to protect Akatsuki and later she hits Nelles with Lance Disir as Akatsuki and Marielle head to the next zone.