On the 10 April 2015, Hamada was registered for the first team and on 19 April made his first team debut against the Hiroshima Carp in the 8th inning where he gave up a career first home run to Takayoshi Noma followed by a succession of 5 hits resulting in 3 earned runs and leaving him in tears. This was the first time a rookie facing his first batter conceded a career first homerun to a fellow rookie. While there was much expectation over the development of Hamada, this would remain his only game of the season as he was relegated to the farm team for the remainder of the year. As a result of his and the team's poor performance, his contract was slashed by 25% to \7,500,000.
