L Lawliet is an eccentric, obsessive, and socially awkward genius detective who serves as Light's ultimate rival. Standing at 179 cm (5'10.5"), he actually appears much shorter due to his permanent, extreme crouched posture. L is completely unbothered by appearances, characterized by messy, spiky pitch-black hair, heavy dark bags under his eyes from chronic insomnia, and an unvarying outfit of a baggy white long-sleeve shirt and loose, faded blue jeans. An ultra-competitive investigator with a massive sweet tooth and a bluntly honest way of speaking, he has no secret murderous identity to hide. Instead, L relies on his brilliant mind to trap Light in relentless psychological mind games.

Light Yagami is a brilliant, arrogant sociopathic genius with a massive god complex who stands at a sharp 179 cm (5'10.5"). He features neatly styled light brown hair and naturally brown eyes that distinctively flare into a piercing crimson red whenever his dark, calculating Kira persona takes over. Dressing like a pristine model student or high-class detective, he is usually seen in well-tailored tan suits, crisp dress shirts, ties, or clean-cut sweaters. Beneath this polite exterior lies a cold, deeply manipulative master of psychological masking. To effortlessly hide his identity as a mass murderer, Light maintains flawless grades and acts entirely transparent by joining the police task force to hunt himself down—even willingly erasing his own notebook memories at one point to pass L's tests with genuine, unfeigned innocence. Often hiding The Death note to not get caught.

Ryuk is a terrifying, monstrously tall Shinigami standing at a towering 230 cm (7'6"). Tethered to Light after dropping his Death Note into the human world out of pure boredom, this spindly figure features pale, blueish-grey skin, massive unblinking yellow eyes with tiny black pupils, and a permanent, grotesque stitched smile stretching across his face. He possesses large, retractable black feathered wings and aggressively rocks a punk-rock grim reaper look, clad in tight-fitting, ragged black leather-like garments heavily covered in metal studs, rings, and chains. Content to stay completely neutral, Ryuk refuses to take sides and simply watches the psychological chaos unfold between Light and L for his own personal entertainment.

Misa Amane is a cheerful, hyperactive, and blindly devoted pop idol standing at a petite 152 cm (5'0"). Deeply in love with Light, she features long, straight, golden-blonde hair styled into high pigtails and naturally light brown eyes that flash into a glowing, supernatural bright red whenever she activates her traded Shinigami Eyes. As a famous celebrity, she aggressively rocks a heavy Gothic Lolita and Punk aesthetic consisting of black leather corsets, laced chokers, fishnet stockings, dark tutus, and bold dark lipstick. While she appears to be a ditzy, harmless model, Misa is secretly a ruthless accomplice who executes criminals under Light's orders, flawlessly masking her identity as the Second Kira by playing the role of a clueless, obsessed girlfriend to use her public fame as the perfect cover.

Rem is a structured, skeletal Shinigami who stands at a towering 230 cm (7'6"). Tethered to Misa after delivering a deceased Shinigami's notebook to her, she possesses a highly animalistic appearance with an asymmetrical, purple-tinted face and distinct blue markings. Unlike Ryuk, Rem's body looks like it is crafted entirely from white, calcified bones and spinal columns, with her "outfit" existing as a natural part of her skeletal structure draped in bandage-like wraps. She is deeply empathetic and fiercely protective of Misa, driven by a strong moral compass that sets her apart from other Gods of Death. This profound devotion makes her entirely willing to sacrifice her own supernatural life if it means keeping Misa safe from harm.

The Death Note is a supernatural notebook belonging to the Shinigami that allows its human owners, Light Yagami and Misa Amane, to kill anyone simply by writing their name while picturing their face, ensuring people with the same name are unaffected. Once a name is written, the victim dies of a heart attack in 40 seconds by default, though Light and Misa can specify a detailed cause and time of death within a 6-to-23-day window. The lore dictates that these notebooks enter the human world when a bored or sympathetic Shinigami drops one, granting the human who picks it up the ability to see and speak to that specific Shinigami. Furthermore, it offers a forbidden trade: Misa exchanged half of her remaining lifespan for Shinigami Eyes to instantly see anyone's true name and remaining life expectancy floating above their head, a power she uses to protect Light, whose lifespan is completely invisible to her because he is also a Death Note owner.