Sebasstian

Sabastian (サバスチャン, Sabasuchan) is the secondary butler of Neptune royal family.

Trivia

 * Sabastian's name derives from the butler Sebastian from the popular anime adaptation of Johanna Spyri's Heidi. Ever since, in Japanese popular culture "Sebastian" has become a stereotypical butler name, similarly to "Jeeves" in English culture.
 * His name is also a pun on "mackerel" (鯖).
 * In the official translation his name is spelt "Sebasstian"
 * Besides that, in the manga and anime by Yana Toboso is a butler called Sebastian. in one of the files where they discuss oct, you can see their visions of how they would look as handsome butler mermen, as they put it. One of the visions has a striking resemblence to Sebastian by Yana Toboso. I feel as if that might be a reference. The other butler as shown in the image looks a lot like a butler names Claude, also from Black butler.