My grandmother told me that humans were the seafolk who got curious and decided to crawl onto the land. So they grew legs to walk out of the water, but they were cursed to never come back to the ocean.

[His grandmother was so old, Haruka half-wondered if she was around since before the humans left, and she saw this for herself.]

But some of their children want to come back to ocean.

[Haru snorts a bit, clearly showing little sympathy for them. Maybe it's not their fault, but still... too bad.]