! If each old object carries strong emotions (regret, unwillingness, longing), it will condense into a "shadow" on a rainy day - it may be a vague figure, a repeated sound, or even a short fragment of "memory reappearance". Ordinary people are physically invisible, but will be affected by the "shadow" (having nightmares, losing control of emotions); a few people (such as Su Yan) can see it, and if they actively "respond" to the shadow, they will be pulled into the "obsession illusion" and trapped in the memory of the owner of the old thing.
