Mission Mermaiden Hasumi And The Deep Sea | Sist Verified [updated]

The game blends traditional platforming with "battle" elements where the protagonist's physical and mental state are central to the mechanics:

As Hasumi, you seem to be on a mission to cleanse or repair this Syst. But who gave the mission? And is the Syst keeping the ocean alive, or killing it? mission mermaiden hasumi and the deep sea sist verified