Kissing sex with a nephew burning from a crash KISS

My sister's son, Masato-kun, was forced to stay at our house for about two weeks to take a summer course at a major prep school in Tokyo. Seeing Masato-kun, who was a spoiled man when he was young, grew up into a great man, I felt the charm of him not as a nephew but as a man. One day, a random incident touched Masato's lips and my lips. "This is an accident, it's not a kiss..." I told myself, but I couldn't forget the touch of my lips, which I had experienced for the first time in a while...