rash, addiction, craving, habit
癮 centers on a persistent, often harmful condition that takes hold of a person: a physical rash or an internal compulsion like addiction, craving, or a deeply ingrained habit.
癮 combines 疒 (sickness) with 隱 (hidden, conceal), suggesting a hidden or lingering illness. The character likely expresses a condition that is not immediately visible but persists internally, such as a chronic rash or an addiction.
The sickness enclosure 疒 wraps around 隱 (hidden). Picture a hidden rash under the skin or a secret craving that you can't see but keeps itching—癮 is that persistent, hidden condition.
For イン, imagine an inn where people secretly indulge their hidden cravings: inn -> イン, and the hidden habit grows inside the sickness enclosure.