A cinematic, realistic scene inside a traditional Catholic church during Mass. In the foreground, a young adult nun in a classic black-and-white habit is discreetly bent forward in the front pew, her skirt lifted just enough to expose her bare ass. She is quietly fingering her own asshole with two fingers, expression a mix of restrained pleasure and tension, trying to stay silent. Soft church light falls on her pale skin and the folds of her habit. In the mid-ground, a priest in liturgical vestments stands at the altar celebrating Mass, holding the host, facing the congregation. Rows of worshippers sit in the pews with their backs partly turned or looking toward the altar, unaware. Warm stained-glass light, incense haze, wooden pews, stone columns, sacred atmosphere contrasted with the secret explicit act in the foreground. Highly detailed, photorealistic, shallow depth of field focusing on the nun while the Mass remains visible and sharp enough in the background, discreet erotic tension, 8k, cinematic lighting.