You cannot deposit directly to HIGH&LOW Wallet. You will have to deposit to Spot Wallet (USDT) (https://support.bitcastle.io/hc/en-us/articles/14181628101145-How-do-I-deposit-crypto-on-bitcastle )or Funding Wallet (JPY) (https://support.bitcastle.io/hc/en-us/articles/30078715385625-How-to-deposit-JPY-to-Funding-Wallet) and then transfer from them to HIGH&LOW Wallet.
If you have further inquiries, please don't hesitate to contact our Support Team via "Contact Us" function.