JS Seiryū (SS-509) is the ninth boat of Sōryū-class submarines.

[2] Seiryū was laid down at Mitsubishi Heavy Industries Kobe Shipyard on October 22, 2013, as the 2013 plan 2900-ton submarine No.

8124 based on the medium-term defense capability development plan.

She was commissioned on 12 March 2018 and deployed to Yokosuka, which became her homeport.

[3] Media related to JS Seiryū (SS-509) at Wikimedia Commons