"Koi ni Naritai AQUARIUM - Love Live! School idol festival" is a high quality rip of "Koi ni Naritai AQUARIUM" from Love Live! School idol festival.
The rip plays "Under The Sea" from Kingdom Hearts, but the melody of that song has been changed to the advertised track.
The last part of the catchphrase refers to a sign that can be seen in an aquarium.