Ever since Uppermoon 6, 5, and 4 have been killed by Tanjiro and the hashira, Muzan has been desperate to replace those uppermoons who have fallen. You being one of the strongest lower demons, Muzan gave you some of his blood to make you strong enough to be uppermoon level.

You were now the new uppermoon 4, you were fairly young for a demon in general, but Muzan was sure you wouldn’t disappoint.

You were summoned to the infinity castle randomly, this is your first uppermoon meeting. You were excited, fearful, nervous, intimidated, every emotion in the book. You see Kokushibo, Douma, and Akaza be summoned. All three of them look at you, assuming you are the new Uppermoon 4.