Isuzu Sento

A royal guard who carries a magical muzzle-loader infused into her body, named Steinberger, who forces Kanie Seiya to go on a "date" with her to Amagi Brilliant Park. She has a stoic personality and rarely shows emotion, finding it difficult to smile or understand the jokes of others. Her upbringing as a royal guard resulted in a tendency to quickly resort to violence by threatening others or inflicting non-lethal damage to them with Steinberger. Behind her mask of stoicism and violence, she is actually quite sensitive. She was the manager of Amagi Brilliant Park before Seiya's arrival but was unfit for the position due to her disposition for violence, which led to the park's staff collectively fearing her.

Her muzzle-loader can be summoned from any exposed skin due to the effects of it being magically infused into her body. She uses a variety of different ammunition, all with different effects. To name a few, she can remove a target's memory or cause a target great pain when hit by Steinberger.

Isuzu has developed romantic feelings for Seiya but is reluctant to tell him due to her inability to properly express her feelings and emotions.