Prior the storyline of the series, Ebina used to live on a water planet where all his habitants couldn't live without it. At some point, the planet got dry and everyone was forced to leave. Ebina arrived on Earth and has lived on a lake since then. However, the people back then were scared of him and he always was alone. One day, he meet Hayashi Fuyou, who also was lonely, on the lake shore and the two became friends. Fuyou told Ebina that she wanted to swin but she can't because of a lung disease. Ebina then promised her that he would protect his lake until she is cured and be able to swim with him.
The Yorozuya knew that the girl probably had died time ago, but Gintoki choose not to tell Ebina.
Ebina is a amanto with green skin and hair. He wears a pair of glasses along with a fundoshi, a traditional Japanese undergarment.
Ebina seems to be someone very friendly and cordial, as he promised Hayashi Fuyou that he would protect his lake until she is cured and be able to swim with him. He can become angry if someone disturbs the peace in the lake or touch the plate on his head.