If you sent BTC to the Zaif Exchange from an external wallet or so,
you should be able to see a Transaction ID. If you, for example, access this site:

https://blockchain.info/ja/tx/YourTransactionID
you can check the status of your BTC transactions.
(*Insert your transaction ID after tx/ )

NB
Please note that we cannot check the status of a deposit made from an external hot wallet
before it has arrived at Zaif.
Also, it may be delayed due to the amount sent or external factors at that time. Please refer to the below as well.