Ishioka started playing rubber-ball baseball in elementary school and while at junior high school played for the Kobe Sky Dragons.
He played for St Michael's Senior High School and in Autumn of his junior year nailed down his spot as starting first baseman. In his senior year, his school played in the Spring senbatsu tournament where Ishioka struck out twice in the first and only game leading to the team's exit. After graduation, he went to play for JR East.
Ishioka contributed to JR East's victory in the 82nd Intercity baseball tournament, picking up rookie player of the tournament honours.[2] In his second year as third batter in the line-up, he helped the team to become runners-up and in 2014 he was selected to represent Japan at the 17th Asian Games[3] where he along with future team-mates Issei Endō, Masataka Iryo and Shun Ishikawa claimed the bronze medal.[4]
In the lead up to Spring training he complained of lower back soreness and on 28 January Ishioka underwent surgery for an intervertebral disk hernia.[6]
Ishioka was the only rookie of the 2015 draft class not to make an appearance during the 2016 season. He did however perform well in the Western League farm team registering a .289/.355/.329 slash line.[7]
^"Overview of the 17th Asian Games". Samurai Japan - The Official website of the Japan national Baseball team. 1 October 2014. Retrieved 23 August 2016.
^"【中日】アジアWL派遣の4野手「合言葉は開幕1軍」" 【中日】アジアWL派遣の4野手「合言葉は開幕1軍」 [Chunichi: 4 position players loaned to Asian winter league; "motto is starting day roster".] (in Japanese). Sports Hochi. 22 November 2016. Retrieved 15 December 2016.