Elucia or Elsie(エルシィErushi?) as she is commonly known, is the series' Deuteragonist and Keima's partner. Elsie is a 300 year old demon from Hell who has been sent to Earth to capture evil spirits that have escape from Hell as a Spirit hunter. Despite her age, she acts rather childish. Elsie has a sweet, pure and innocent personality but is rather clumsy and easily distracted which causes Keima to consider her unreliable. Despite these faults, Elsie is always trying to please Keima and convince him that she is a reliable partner.
At the start of the series, she gets Keima to agree to a contract to help her catch spirits through an email and under the belief that he was a womanizer only to learn the awful truth that he misunderstood her email and is actually a womanizer of game girls. However, she manages to convince him that the girls in real life are similar to game girls thus saving both their lives should he refuse. With her help, she assist Keima in conquering the hearts of girls so she can catch the evil spirits inside of them. In order to be close with Keima without suspicion, she becomes his younger sister(and calling him "Kami-nii-sama"(Divine Brother)) by giving a letter (written by her boss) to his mother, Mari, which claims she is her husband's illegitimate child, living in the Katsuragi household as well as attending the same class as him. Due to her outstanding performance in capturing spirits, she receives an Award for her hard work, much to shock to some of her demon friends who usually know Elsie as a klutz.
Prior to the story, she was a cleaner for 298 years until she was recruited to the Spirit hunters as there was a need for more hunters to help catch the evil spirits on Earth. Elsie took the opportunity as this allowed her to follow in her older sister's footsteps who is a famed Spirit hunter. Elsie is always seen with her magical raiment, a floating long scarf which can change the appearance of an object, help her fly and create disguises or hide people in plain sight, a skull headband that detects spirits and a magical broom from her previous job.
There are several running gags about Elsie which includes her cooking, while pleasing and delicious to demons like her, is disgusting to humans due to use of ingredients from Hell. Another is her misunderstanding of modern culture due to cultural differences which has led to some comical situations and her love for fire trucks.
Due to her friendly and cheerful attitude, she has made a lot of human friends, which some ironically are the same girls whose hearts Keima has captured before their memories were erased. Despite being her "husband's illegitimate child", Mari adores Elsie and treats her like her own daughter. She is a big fan of the pop idol singer Kanon and is also in a rock band called the "2B Pencils" together with her friends Ayumi, Chihiro, Yui and Miyako with Elsie as the bassist. When Keima begins searching for the Jupiter Sisters, he decides to rely upon Elsie's friend Haqua instead as the latter has the expertise and knowledge he needs. But when Kanon is injured by a Vintage assassin, Keima has Elsie disguise and pretend to be Kanon in order not to cause a commotion and suspicion in public.
