Synergy Japan Anime

After the final battle against Gaito, Sara had given her life to remain with him. The sea world is now at peace, but only with six mermaid princesses.

While Caren, Noel, and Coco have returned to their kingdoms, it should be time for Lucia, Hanon, and Rina to do the same. After all, Mitsuki Tarou is leaving for , and Doumoto Kaito is heading to Hawaii. Lucia is devestated, and when things couldn't get any worse, Kaito is lost at sea! Worst of all, a strange angel named Michel has appeared, wanting the mermaids to him. But on the lighter side, Sara's spirit tells Lucia of Sara's successor, a young mermaid named Seira. The mermaids are in for another adventure!

(Source: AniList.co)