A young girl living in peace as a hunter sees her life forever changed when a new threat comes for her sister.

Nanoha & Fate recruit Shiina to EXCEEDS, and explain the Diaboli. / A mysterious group of girls slay Diaboli.

On her day off from EXCEEDS, Shiina encounters Towa attempting to rescue a cat & the two become fast friends.

Shiina is killing progenitors while Towa prepares to make her move, reflecting on the reason for her actions.

EXCEEDS & the Diaboli Slayers run into each other as both target the facility abusing Progenitor Three & Four.