in Welterweight boxing, for the vacant world title of International World Muaythai (IWM) title at Super welterweight. Masato was unprepared for Suriya's southpaw style and was dominated for the entire 5 rounds. Originally Masato was scheduled to fight Orono Por.Muang U-Bon but due to the speculation that Orono had Hepatitis B, Masato's team opted not to fight, only days before the event. K-1 WORLD MAX 2002 Masato participated in the 2002 K-1 MAX Tournament on February 11, 2002. This tournament was televised all around Japan by the Tokyo Broadcasting System (TBS), and the directors introduced Masato as "the Rebellious Charisma" (反逆のカリスマ) for their advertising slogan, and they continued to use it whenever Masato was on television. Although it became commonly known, Masato hated his new nickname and said "Stop using it" during an interview, because he did not understand what Rebellious stood for. He beat Takayuki Kohiruimaki, the only person who had beaten Masato before among the Japanese fighters, by unanimous decision at the tournament final. After the tournament, Kohiruimaki said "I'll fight against him again and kill him without fail" in the ring to the audience). On May 11, 2002, he participated in the K-1 World MAX 2002 World Tournament Final. He beat Duane Ludwig by unanimous decision in 3R. In the next fight, he was knocked down by Albert Kraus at 2R and lost by unanimous decision in the semi-final. Masato fought in his own event, "Wolf Revolution". He fought against Melvin Murray from Canada, and knocked Murray out with low kicks in the 2nd round. K-1 WORLD MAX 2003 On the 5th of July 2003, Masato was invited again to join the K-1 World MAX 2003 World Tournament Final. He defeated the Greek kick-boxer Mike Zambidis in the quarter finals by a split decision, after a close fight. He then moved on to the semi finals to fight Thai kick-boxer Sakeddaw Kiatputon whom he defeated via a Right uppercut KO. Masato then moved on to fight in his first K-1 World MAX final for the title against Albert Kraus, whom he lost to at the K-1 World MAX 2002 World Tournament Final via decision (Kraus went on to win the title), and also again fought Kraus later that year at K-1 World MAX 2002 Champions' Challenge which resulted in a decision draw. Masato finally managed to defeat Kraus via a left hook knockout in the 2nd round