Esna is a non-playable main character in Ever Oasis. She is the last Water Spirit, and together with the main character Tethu/Tethi, they create the last Oasis! Together they find ways to protect their Oasis from the ever present chaos that tries to swallow it.
As a Water Spirit, Esna is unable to leave her spring, but always wanted to see what lay beyond the confines of her lake. By using a drop of water filled with her powers that is carried by the desert beetle Khepri, Esna is able to communicate with Tethu when he leaves the spring and travels around the Oasis and the desert beyond as well as experience all the thrills of Tethu's adventures.
Water Spirits can only be seen by Children of the Great Tree, like Tethu, who have the ability to become Chiefs of Oases, so Esna is unable to communicate with any of the other residents of the Oasis, and while they may mention the existence of a Water Spirit in the Shrine of the Great Tree occasionally, none call her by name, as they have never met her.
"Have you noticed the Spring of the Great Tree lights up sometimes? If you use Green Gale where it's shining something good may happen to you!"
"There used to be many Oases around, but now this is the only Oasis left.. Tethu, together we can work hard to make this a thriving home for everyone in the desert!"
"When the desert gets so hot, it's hard to travel on foot... i wonder if you may find some travelers taking shelter inside a hole or under some rubble."
"Nighttime brings out tough Chaos monsters. Be careful!"
"Lili was quite surprised to see the fruits from the garden. Unlike the garden in the Oasis, the desert may not have a place to grow some of the larger fruits...""There used to be a lot of water spirits around. Now I'm the only one left here in this desert... I was feeling lonely, but i'm fine now that I've met you, Tethu!"