Added the "tagme" tag because perhaps now that it's in huge-o-vision, the characters are not who they were originally believed to be, specificially sakura and gilgamesh.
That definitely looks like Sakura in the back. Asagami Fujino has a different hairstyle without a ribbon, and I think her hair's more of an indigo color anyway. And besides the haircolor the guy in the water still looks a lot like Gil.
Yeah, it's definitely Sakura. The ribbon is a dead giveaway, her hair is right, and it looks like she's wearing the bikini that Sakura wears in HA, too.