User blog comment:B214/Question and Answers/@comment-213.106.131.123-20131115233123/@comment-213.106.131.123-20131116105801

On the HighSchool DxD website Poseidon's wiki page says he appears in a short story, and in volume 10 when Zeus and Poseidon get introduced Issei says he has met Poseidon before? When and how did he meet him?