Whilst Koki obviously meant it as a tongue in cheek bit of fun many jumped on him denouncing him as foolish for such a joke whilst other fans seemed to make it clear they wished it was a joke but actually a genuine retirement.
Although one of Japan's most famous fighters Koki is certainly not a popular fighter. In professional wrestling terms he has built himself us as "the heel", the bad guy, unfortunately for him it's probably gone a few steps too far and it's not that he's just disliked by some of those in the Japanese boxing community but he is actually despised by some who are hoping to never see him in the ring again.
Whilst his "April fool" may have gone down like a lead balloon there is some talk about Koki becoming the mandatory challenger to WBA Super Flyweight champion Kohei Kono with the fight now rumoured to be in either Mexico or Macau. These are still just murmurs but could well lead to something with Kono himself talking about fighting in Macau.
(Image courtesy of Koki Kameda's ameba.jp/ account)