I'll Give You a Golden Finger

This time, I'm sticking to my silly, sweet, and naive approach, no matter what~ Here's a little more about the setup, in case it gets confusing. The Sun family guards a forbidden land, where a divine power is enshrined. When A is willing to offer up their life to this power and ask it to grant B a golden finger, the divine power turns into a copper key. Once the sacrifice is complete, the divine power transfers from the copper key to B. B is reborn, A dies, but their soul remains in the world until the wish comes true. Only the sacrificer themselves, as a ghost, can reclaim the divine power from B and transfer it back to the copper key. Because the person who stole the divine power was already prepared to sacrifice their life, the original divine power had turned into a copper key. But when the ritual was interrupted, the original copper key split into several keys. There are nine copper keys in the nine worlds, all split from the same source of divine power. The golden fingers have different levels of durability depending on how much divine power each received. Some break after just a few uses, while others can be used for a long time. Theme: