As one of the founding members of Rhine Lab together with Saria and Kristen Wright, Muelsyse, the director of R.L.'s Ecological Section, has been dedicated her life to bring contribution both to the company and to herself. Notably, being one of the few surviving Elves living in modern cities, she is fascinated by their tales yet pities their ultimate fate of contacting Oripathy. As she learnt more of her deceased parents, she deemed that the current condition of Terra is no longer hospitable to the Elves. Thus, she has been searching for her surviving kin and hope to unite them under one banner and search for a new homeland.

She wants to mend the broken friendship between Saria and Kristen, yet she has to protect herself from the Columbian Department of Defense that manipulates the company's affair through the support of Ferdinand Clooney. As a matter of fact, many R.L. staffs such as Dr. Olivia Silence note that she is capable of ruthless scheming despite her friendly nature on the outside. Nevertheless, she faithfully stands on Kristen's and Saria's side in any matter and has been assisting them in numerous important matters such as diving deep into the background evidences of the "Diαbolic Crisis" under Saria's request and fooling the D.O.D. in the "Project Horizon Arc" to help Kristen.

Along with her unique Elven traits, Muelsyse is skilled in hydrokinetic "magic" that isn't related to Originium Arts. She can materialize water out of nowhere, manipulate water molecules in the air to lower the surrounding temperature, and create a water doppelgänger or decoy capable of convincingly fooling others. As a matter of fact, she is an important asset to both R.L. and Rhodes. Especially to the Doctor, she is indeed a loner of her race who yearns to find companions on her side, hence bringing blossoms in the empty room of their hearts.

— So you're saying I have the right to decide your schedule and itinerary? Which means, whatever I write in this memo book, Doctor, you've gotta do. Wowie! Too late for regrets.