Nachtmusik Zero ~Jogen ni Shinshin o Sasagu Niritsu Haihan no Maid~

The night before Alec inherits the title of fourth-generation royal court 'trainer', he and his attendant Millie brace for their final test.
Now they must prove their skills—on each other.
They’ve trained side by side since childhood, but this? This makes their skin prickle with something sharper than nerves.
Neither will admit hesitation. They lock it away, faces schooled to ice, and begin.
But the mansion breathes decadence into their lungs. The weight of generations presses down. Their discipline cracks.
Shame burns off like mist. What’s left isn’t master and servant—just hunger, and the dark pleasure of surrender.

[Rewritten from digiket]