Tokashiki compiled a record of 13-1-1 (2KOs) before challenging Hwan Jin Kim for the WBA Light flyweight title in December, 1981. Yoko Gushiken had lost the WBA title to Kim, after defending it 13 times, and Tokashiki set out to avenge his gymmate's loss. Tokashiki won the world title with by unanimous decision, but a scandal involving the Kyoei gym's management was revealed the same day, and Tokashiki's victory was marred by controversy, since he and the previous champion, Gushiken, both trained with the gym.
Regardless, Tokashiki compiled 5 straight defenses, but lost his title to Lupe Madera, (who he had fought two previous times in defenses) after he was injured in the 4th round. Tokashiki got a rematch in October, 1983, but lost a close unanimous decision in 15 rounds. The WBA would have allowed another rematch, but Tokashiki did not want to fight Madera for a fifth time, and decided to challenge Korean boxer Jung Koo Chang for the WBC Light flyweight title instead.
The match took place in Korea, where Chang was already a national hero. This was the only time Tokashiki fought outside of Japan in his career, and he knew he had to win by KO to capture the title. Tokashiki was aggressive from the first round, and pinned the champion against the corner, when he was knocked down for the first time in his career with a counter left hook. However, Tokashiki managed to tire out the champion by the 5th round, and Chang showed fatigue, clinching repeatedly, and slipping in the 8th round. Chang's corner bought time by having to retape the champion's gloves twice during rounds, and in the 9th round, Chang surprised Tokashiki with a sudden flurry of punches. Tokashiki was unscathed, but the referee immediately stopped the fight to declare Chang the victory, despite the fact that Tokashiki had shown no signs of being hurt, and remained standing as Chang collapsed to the canvas after hearing that he had won. Chang was only 21 years old at the time, and rebounded after this disappointing finish to defend the WBC title 15 times. Tokashiki announced his retirement shortly after this fight. His record was 19-4-2 (4KOs).