Hikari to mizu no Daphne (TV series)

In the distant future, the earth is almost entirely covered by the ocean, with only small islands and floating cities on the surface. 15-year-old Maia Mizuki is turned down by the prestigious Ocean Agency, despite her exceptional skills and superior grades. After finally being evicted from her home, she joins the Nereids squad, a group of bounty hunters who seek fugitives from justice and other dangerous missions. - IMDb