So that's what the Octolings are gonna look like.

Not quite what I imagined, but nonetheless good-looking all around.

Hopefully they'll have customization options as well. Would love that big octling hairdo that you see on the enemy types.

I haven't played Splatoon myself but I am curious about the back story behind the rivalry of the Inklings and Octolings. Do the games give any details on this?

Monki said:

I haven't played Splatoon myself but I am curious about the back story behind the rivalry of the Inklings and Octolings. Do the games give any details on this?

I haven't either, but from a bit of googling its a fairly standard land conflict, with post-apocalyptic rising seas putting available living space at enough of a premium for them to have ended up fighting over it in the past.