Maria Aikaterina Cerventes, also known as Aika is a popular girl in her school. She was living a life with such fortune that anyone would wish for-- high grades, good friends, a nice boyfriend, wealth, and a happy family. Until one day, her boyfriend transformed into a hideous monster in front of her all of a sudden and willing to kill her without mercy. Scared and confused, she was caught in a life and death situation until someone came up to save her. Jerome Hamilton, a mysterious guy wearing a black hoodie, and using a scythe with unbelievable powers that he uses to defeat those monsters called Unholy creatures. And after that first encounter, Aika started to lose everything that she had in her life until she ends up with nothing. Amidst her devastation, she ended up in a place called Underworld, where different kinds of beasts or night-crawlers were living. Left with no choice, she enrolled at the Underworld University, where the beasts are training to be an Unholy Spirit Hunter.

Roma Cassandra Martinez is a cute yet boyish high school student in her tenth grade. Unlike other girls at her age who are already experiencing crush and puppy love, Roma only knows eating, sleeping, playing DOTA, binge watching and drawing anime. And also bonding with her few close friends. Everything was all fine and normal in her simple life. Until one day, her parents told her that they've decided to engage her into an arranged marriage. She can't believe what her parents have done and it made her feel frustrated and disappointed, especially they informed her exactly her birthday. Truth to be told, relationship, marriage and anything that were related to love and romance were never Roma's interest. The heck, even having a suitor never crossed her mind. For her, the idea of romance was a stupid nonsense and love is just something that shouldn't be prioritized in life. Until she knew that she needs to marry this man whom she never know in order to save her parents from their million-worth debt.

Si Charlotte Revilla ay isang mag-aaral sa ikalabing-isang baitang sa isang pribadong high school. Isa rin siya sa mga natatanging estudyante sa kanyang klase at kilala rin siya sa kanilang paaralan bilang Vice President ng Student Council. Isa siyang huwarang mag-aaral na may maayos at simpleng pamumuhay. Hanggang isang araw ay nagbago ang kayang buhay nang mapadpad siya sa silid-aklatan ng kanilang paaralan at kanyang natagpuan ang isang antigong salamin na nakatago sa bodega nito nang sundan niya ang isang misteryosong pulang paru-paro. Lingid sa kanyang kaalaman, dahil sa antigong salamin ay nabuksan niya ang lagusan patungo sa mahiwaga at kakaibang mundo na tinatawag na Aglaea. Samahan si Charlotte sa kanyang pakikipagsapalaran na harapin ang mga pagsubok sa mahiwagang mundo ng Aglaea bilang ang hinirang na Magíssa.