Iwasa achieved the triple crown of selection, inter-school athletic meet, and national polity in the third year of high school. After experiencing 66 amateur games and graduating from high school, he made his professional debut in 2008. Became the IBF World Super Bantamweight Champion in September 2017. In the second defense match in August 2018, he lost the decision to Terence John Doheny (Ireland) and fell to the throne, but in the provisional title match in December 2019, he was ranked third in the same class as Marlon Tapales (Philippines). He won the TKO 11 times and became the provisional champion. It will be the first match in 1 year and 4 months since then.