In The Rescue of Mermaids, you play as Garry, a human-looking creature who possesses a curse that turns him into octopus, to keep himself in human form he needs to be aroused, and for that he has a small harem with 3 mermaids who are his companions of adventures and love.
One day Garry was relaxing when a horrifying creature appeared and captured all the mermaids at once, leaving Garry alone. Now he must seek and release his companions if he wishes to freely enjoy the human form again.
Garry (the player): The cursed octopus that you embody
Sushi: The blonde and younger mermaid
Seiko: The most serious mermaid with blue hair
Jill: The older and more aggressive redhead of mermaids
Crab girl: First monster girl to be found
Anemone girl: Second monster girl found
Oyster girl: Third monster girl found
Nudibranch girl: Fourth monster girl found
Moray eel girl: Fifth monster girl found
Squid girl: Sixth monster girl found
Marin: First boss
Shub-Niggurat: Second boss
Cthulhu: Last boss