Kyonyuu Musume o Suimin'yaku de Nemurasete

A girl of some vague family relation came to visit. She's very obedient when my mother is watching. But, when it's just us, she's an insufferable brat. "Damn it! I'll get back at you somehow, you little--!" I remembered that my doctor had prescribed sleeping pills from before. "Perfect...... This will put her lights out......"