Celliera is a playable character in Dragalia Lost.
A woman who trains nobles in the way of the blade. Though thought of as a kind older sister, her ferocity is unleashed once lessons begin. But that's just another side of her sisterly love, as she desires her students to become strong.
Official Description (Summer Celliera)
The armsmaster may have taken the beach by storm in a fashionable swimsuit, but she hasn't forgotten any of her fiery instructor's spirit. No amount of heat will interfere with her need to train—that's just how she enjoys her vacations!