But for his efforts, Mayweather earned a cool $9 million payday.
Mayweather's declaration might disappoint those who were hoping he'd return to the ring to fight UFC superstar Khabib Nurmagomedov or fellow ageing boxer Manny Pacquiao. Mayweather was gracious in victory, hugging the weeping Nasukawa and calling him "still a great champion".
Sensing his opponent was struggling, Mayweather stepped in for the kill, unleashing a flurry of punches that left Nasukawa reeling again within just two minutes of the bout and facing his second standing count.
The results will not go against either fighter's win-loss record.
The bout was scheduled for three 3-minute rounds, but Mayweather needed only one as he came out throwing heat from the very start.
"We are both still undefeated", Mayweather said, per The Mirror's Jake Polden. "Would you do the same if you were me?" "Thank you to the fans you guys have been incredible". Toyko, Japan - you guys are awesome - I want to say "Thank you". "I like to call it a nine-minute walk thru", the post added. "I'm still 50-0", according to ESPN's Ariel Helwani. "I'm still retired - I don't look forward to coming back to boxing but I wanted to do this to entertain the fans in Japan".
Floyd Mayweather's quick finish in his latest fight has received quite the reaction from the MMA community.