He makes appearances in V Jump and some video games.
The name "Umiuma" appears to be a direct reference to the name "Kaiba". In Japanese, both names are spelled 海馬, but they use different readings of the same characters (the on'yomi and kun'yomi, respectively).
The words "umiuma" and "kaiba" can both be used to mean "seahorse" (or, by extension, "hippocampus"). It is not clear if the title "Kaiser" was chosen in reference to Kaiser Sea Horse, a card which was used by both Seto Kaiba and Kaibaman.
In Yu-Gi-Oh! GX Tag Force, he is involved in a feud with Sanzyudai Yuki, and asks for the player's aide in defeating him. He appears in the morning at the Volcano after the player has completed the Story Mode with 3 or more Page 1 characters.
In Yu-Gi-Oh! GX Tag Force 2 , to Emperor.Umiuma's annoyance, he is partnered with Sanzyudai Yuki, and in order to be allowed to change partners, he must duel at least once. He challenges the player and his Partner to a Duel, and upon victory, he allows the player to partner with him. He appears during a Random Event at the Main Gate after the player has completed the Story Mode with 4 or more Page 1 Characters & have beaten Jaden & Chazz in duel 15 or more times each.