One very bored devil king.

Akito, Agito, and Lind Wanijima are three persons inhabiting the same body. Agito, Akito, and Lind are an effeminate-looking teenager with a slight build and shoulder-length, dark blue hair. They are 14-15 years old when first introduced, aging only 6 months as the series progresses. They are 142 cm (4'8") tall, weigh 38 kg (84 lbs) and have blood-type AB. As Lind, he has Over-Cross Twinkle Eyes, spiky hair and fanged teeth.
Lind is the original product of the Brain Charger Project.

Kaiman is the lead character of the manga. He appears to be the victim of a magic user, who laid a curse on his head.
Other than that, he has no recollection of his previous life. He has the head of a large reptile, with no other alternates in limbs or body. There are cross-shaped marks over each of his eyes.
It appears that despite having his head chopped off, he can regenerate it in a matter of time.

Revy (レヴィ), sometimes referred by her full name Rebecca (レヴェッカ), is the female protagonist of the series. She does most of the fighting for the Lagoon Company. Very little is revealed about her past, although portions can be pieced together through the series. Revy is a Chinese-American born and raised in Chinatown, Manhattan, near Mott Street, spending most of her youth as a thief and murderer. Flashbacks throughout the series reveal that Revy may have honed her skills with firearms by shooting at cans, and that her first murder may have involved shooting an unknown man while using a pillow. It is unknown whether the pillow was used to suppress the noise or to help avoid looking at her first victim.