(Notice) We have posted a guide on support and walkthrough, if you would like to take a look.
https://shirokurohitsuji.studio/en/2021/01/19/rainbowsea_walkthrough_announcement/

Rainbow Sea is an adventure game with beautiful character designs, isometric pixel-arts, nostalgic chiptune-flavored music, and a sometimes amusing, sometimes melancholy plot. You can clear this in a couple of hours, but you can play it again and again as the story changes depending on your choices and actions, and there are many ways to reach a single ending.