Third season of Mushoku Tensei: Isekai Ittara Honki Dasu.

Narukami Ryusei is your typical NEET. He spends his days shut in his room playing video games without a care in the world, living a lazy life. But the truth is, Ryusei used to be a powerful demon king in another world! So why not spend this new life doing whatever he wants? Except, he wasn't the only one reincarnated into this world. The hero who struck him down is here too—and she's a really cute high school girl?! Can Ryusei survive reuniting with his foe in a new world, or will he find himself fighting even in this life? (Source: Seven Seas Entertainment)

Long, long ago, there lived a mermaid princess named Lara. She was raised with love by her father, the king of sea and her sisters. One day, Lara fell in love with a human prince who lived on land. It was a forbidden love—one that was not allowed in the world of mermaids. Still, Lara journeyed to the surface. With a potion, given to her from the witch Grace, she became human. But the potion came at a cost—fail to find true love, and she would turn into foam and vanish into the ocean. Though she was a princess of the sea, Lara chose love. Yet, her wish went unfulfilled and she vanished into the sea. Two hundred years later, Lara awakens once more, in Lake Biwa to finally search for her true love. (Source: Crunchyroll)

Corporate slave Arihito Atobe's death in a freak bus accident marks the beginning of his new life as a kind of adventurer called a Seeker. Reborn into a fantasy world, he settles into a previously unknown job class called rearguard, capable of providing his (all-female) party with critical attack, defense, and recovery support. And it comes with an added bonus: Simply being at the back of the party line increases his companions' fondness for him! Freed from the shackles of corporate life, Arihito is eager to start fresh as a newly minted Seeker! (Source: Yen Press)