Junki Koike

On 9 January 2012, Koike was announced at Tokyo Verdy on a permanent transfer. On 12 January 2014, Koike was announced at Yokohama FC on a permanent transfer. On 30 December 2015, Koike was announced at JEF United Chiba on a permanent transfer. On 29 December 2016, Koike was announced at Ehime FC on a one year loan deal. On 19 December 2017, Koike was announced at Ehime FC on a permanent transfer. On 27 December 2018, Koike was announced at Tokyo Verdy on a permanent transfer. On 7 November 2020, Koike played his 400th J2 League match against Tokushima Vortis. At the beginning of the 2021 season, he was appointed as one of five vice captains. On 25 December 2021, he renewed his contract with the club for the 2022 season. On 7 December 2023, the club announced it would not be renewing Koike's contract for the 2024 season. On 5 January 2024, Koike was announced at Criacao Shinjuku on a permanent transfer.

In 2015, he and his Tokyo Verdy teammate Ryota Kajikawa set up "F-connect", which supports children in orphanages.

Koike's favourite football player is Kazuyoshi Miura. The two ended up playing together when Koike joined Yokohama FC. He later ended up assisting Miura against Júbilo Iwata to give Miura the record of oldest goalscorer in J League history.