Magical Girl Lyrical Nanoha S03 E10 Riot Force 6's Day Off (First Part)

Subaru, Teana, Caro, and Erio are on their vacation. Suddenly, Erio sensed a magical presence, and follows it. To Erio and Caro's surprise, they see a girl coming out of the sewers. What was attached to that girl's foot was a relic case!