this was lovely. not only was the story interesting and well told, but the choices enabled real roleplay (although to be honest i can't imagine another tsumugi not doing *exactly* what i did).
the "ocean entity" had such a fun way of speaking, and i particularly loved: "Well... I might not be when you are right now soon, but I wanted to let you know I was now." so much character and info given through word and tense choice without feeling goofy.
i imagine the final letter changes depending on your choices, which is a very clever finale. really good!