This paper introduced the design and implementation of a credit and liquidity risk model to offer decentralized banking services for the NFT market. We showed that by segregating the underwriting risk from the existing DeFi infrastructure, Zumer is able to manage the credit default risk of illiquid digital assets (NFTs) with a decentralized and permissionless mechanism. The Zumer Protocol enables all stakeholders to determine all the essential parameters involved in NFT-back borrowings. We believe Zumer will become the backbone that supports all Metaverse projects (NFT projects) and allow frictionless movement of liquidity, data, and ideas eventually between chains and communities.