Playing at a senior's house, a first-time game with just the two of us alone.

──Ding dong. Fifth floor, Room 502 of a certain apartment building. When I nervously ring the intercom, the door opens after a moment, and my senior appears, her beautiful long black hair swaying. "Oh, junior, you came. Come on in, come in." My senior forcefully pulls me into the room in her usual manner. To be honest, it would be a lie to say my heart isn't pounding––but I'm dragged along by my senior's momentum and enter her home. ––That's right, today I've been invited over by my senior, and I'm about to experience a game I've never played before...