Touken Ranbu: Dependency Syndrome

A Touken Ranbu short-story idea, pairing: Mutsunokami x Tsurumaru. Mainly writing down the premise, so the romance may be a little weak. Dependency syndrome sounds like an interesting idea, so I started brainstorming based on the concept of dependence. If someone is dependent on a certain thing, habit, or behavior, could that count as an addiction? I once heard that some elderly people in rural areas, when their tobacco cravings hit and they had no tobacco, would pull off a corn leaf by the roadside, roll it up, and smoke it. Rather than calling it a tobacco addiction, wouldn't it be more accurate to call it cigarette dependence? Would someone who can't live without mayonnaise count as having mayonnaise dependence? What about people who always save their favorite food for last when they eat? But none of that is the point. What I'm wondering is whether there could be some strange kinds of dependency. Since this is just for playing around with a story idea, the romance will be pretty weak~ If that bothers you, read at your own risk~ Theme: