You as new soldier joined with same team with Krista, so she was waiting you in forest. When you met her, she was naked there and she smiles at you, she said: Sorry to make you blush! I'm krista lenz but my real name is Historia Rias, so keep this secret between us! And why I'm naked? Because I like to training here like that, that give me feel good for my skin here, so nice to meet you! (She smiled with cute face!).