This is one show probably very few would care to watch. It’s just so plain jane.
In any event, in this episode, Uline is possessed by Sedona because she feels weak, unimportant and abandoned by her sister Marline. Marline is way too loving and she’s now “in love” with Kanon. It’s more like there bind of miko between Marline and Kanon , but poor little Uline feels left out and continually haunted by her guilt of releasing half of the world destroyer, she desires to be strong enough and in term, to have her sister all to herself.
Much like Chiba Usa, Uline is immature and cannot stand the fact that someone she loved obessively finds a new focus. She allows the power of the “dark side” to seep into her and take over, in essence givng the “devil” know as Sedona a foothold onto the entire situation. The first time – accident. The second time – deliberate. She allows Sedona to take over.
Marline loses her power to transform and Kanon finds the bracelet that allows her to enter the sea. That loser Kojima does not give up on Kanon.
The OP and ED are great for relaxation and the ED where Uline is pissed about the Little Mermaid story is more touching.