I'm obsessed with Okeanos. It's a great song. It has an orchestral arrangement with a slapper bass on the build-up. There's an alternate build-up and a title drop towards the end. The singing is like Suzuna trying to tell a story before bed, like a lullaby. It's clear, soft, and you can catch every word she sings out.
https://www.youtube.com/watch?v=m-aKj8QNIJ0 