Are you expecting an inheritance payment - from someone in Nigeria with a Japanese email address??? Of course you aren't. So you don't really think that this is real, do you?
It isn't real. It's a scam. This unimaginative scammer is hoping you will reply - they will then try to take money from you by charging you fees.
Delete the email and don't reply.
It was Resolved and Agreed that your inheritance/Contract Fund would be released on a special method of payment which tag Name Reads SWIFT CREDIT CARD.SEND YOUR NAME,ADDRESS,NEXT OF KIN.PHONE AND FAX NUMBER TO CLAIM YOUR FUND.