The Devil Does Exist (悪魔で候 Akuma de Sōrō?) is a shōjo romance manga based on school life written by Mitsuba Takanashi, it consists of 11 volumes and has already been dramatized in Taiwan titled Devil Beside You.
High school is difficult for most kids. But for Kayano, a shy girl whose single mother seems to work all the time, it's even worse than usual. She's so afraid of drawing attention to herself that she can't tell the handsome Kamijo how much she loves him-until one day she finally gets up the courage to write him a letter confessing her feelings.
But her plans go awry when the letter falls into the hands of the school's most notorious student, Edogawa Takeru. To Kayano, Takeru seems to be Satan himself. Not only is he devilishly handsome, he is the son of the school's principal. To make things worse, her mother comes home to announce she's getting married...to principal Edogawa! Now Kayano will have to live with this devil Takeru 24/7!
But, in an unexpected twist, Kayano and Takeru gradually begin to grow feelings for each other the more they interact, but many obstacles gets in their way, but the biggest one of all was to face their parents who are soon to be married and come clean about their true feelings for each other...how will their parents react? What will happen to the soon-to-be family?
- Kayano Saitou
- Kayano is a shy second year student in high school who lives with her widowed mother. Kayano has a kind heart and can be stubborn sometimes, despite her shy appearance. She learned to grow stronger as the story progresses. The most important characteristic about Kayano is her endless compassion for others. She hates hurting others and tries to bring happiness into people's lives, even if it makes her unhappy.
- Takeru Edogawa
- He is a first year student. The bad boy of the school and the principal's son. He is first seen as a good-looking delinquent who like to cause trouble, but as the story progresses, we see a softer side of Takeru. He is very mature for his age and is protective of people he cares about, often blaming himself if anything bad happens to them. He is a year younger than Kayano. He is not nice even to the people he cares about most. He says things really mean in order to cover up his feelings. He was inspired by a former X JAPAN member - Hideto Matsumoto - who passed away in 1998.
- Rika Moroboshi
- One of Takeru's childhood friend who is in love with him.
- Takeru's childhood friend who harbors a secret crush on Rika. He is very fond of Kayano. Youhei stays with Takeru despite Takeru's attitude because Takeru stood up for him in the past.
- Kamijou Yuucihi
- Captain of the basketball team, Kayano has liked him since the beginning until she met Takeru. He develops feelings for Harukawa.
- Harukawa Kyoko
- One of Kayano's best friends who encourages her to do many things. She is outgoing, strong-willed, and confident. She later becomes Kamijou's girlfriend.
- One of Kayano's best friends.
- Takeru's little brother who went to live with their mother in Europe when they were young. He is introduced as a junior high student towards the middle of the story.
Outside Japan, the series is licensed by Panini Comics in France,  by Tong Li Publishing in Taiwan, and CMX Manga in North America. The series was formerly licensed by Star Comics in Italy.
Carla Cino in the French Animeland described the series as a perfect read between two trains as its neither give headache nor is transcending. Its problem laying to not be much something as numerous manga with similar plot have been read. The "fashion" aspect of the characters and Takeru's pervy side giving a semblance of novelty.
- The Devil Does Exist (manga) at Anime News Network's Encyclopediait:Lui, il diavolo!sv:Devil Beside You