Yahoo Auction Japan payment

So, like a total idiot I won a bid at Yahoo Auction and paid the seller directly by furikomi instead of going through Yahoo's kantan payment system. I was wondering if this in any way endangered my payment, since Yahoo doesn't know that the payment was actually made.

I usually pay by credit card but this time the seller was insistent so as soon as I received his bank details I just went straight to my bank's online site and made the transfer. It was only later that I realized that I didn't do it through Yahoo.

Yahoo doesn't know how you paid or unpaid to the seller.
It's your responsibility to do the auction and Yahoo doesn't take the responsibility.

I don't see any problem with it - as far as the seller is concerned, you have the bank remittance record.
Yahoo!Japan is just providing the "kantan payment" service as an additional service (for a fee, of course).

So, like a total idiot I won a bid at Yahoo Auction and paid the seller directly by furikomi instead of going through Yahoo's kantan payment system.

That is one of the normal ways to pay for Yahoo auctions. Yahoo doesn't need to know that you actually paid.

I was wondering if this in any way endangered my payment, since Yahoo doesn't know that the payment was actually made.

Theoretically it is a little bigger risk of being defrauded since you won't have the backing of Yahoo and/or your credit card company, but its generally a small risk.