This is a posable action figure from the Nendoroid series.
From the Good Smile Company website:
From the popular smartphone game "Shironeko Project" comes a Nendoroid of the dark nun who broke her vows - Mira Fenrietta! She comes with both a standard expression as well as a triumphant expression.
Optional parts include her "Holy Cross" weapon as well as her main source of nutrition - a packet of bean sprouts! She also comes with special parts that allow you to recreate her "Lightning Bolt" and "Holy Heal" skills from the game! Be sure to add the haughty Mira-sama to your collection!