Metamask
Metamask us currently not supported.
Typically a wallet such as Metamask supports EVM-based blockchains and tokens. Koinos blockchain is not EVM-based, but WASM based. EVM-based blockchains are Ethereum and all its clones. This doesn't mean Metamask will not support Koinos ever. At this stage, we are not aware of Koinos blockchain being on the roadmap of Metamask.
Koinos supports a variety of Wallets which are listed on the Applications page.