I casually invite the withdrawn and unapproachable Tsubaki Sannomiya to dinner and am shocked when she accepts. Since I already have a girlfriend, I plan to end the evening after a quick meal, but she asks me to continue drinking at her place. Thinking one easy hookup could be worth it, I agree and sleep with her. The next day, I discover that Sannomiya believes we are now a couple, and her quiet demeanor gives way to obsessive control as she keeps milking me for cum despite my engagement.