OMORI is the titular deuteragonist in OMORI. OMORI can be controlled by the player during the night, where WHITE SPACE can be explored. When OMORI is in the lead, he can cut down obstacles with his knife. OMORI is a young boy who wears a black tank top, long black socks, and black and white striped shorts. He is the only character to be colored black and white in contrast with the colorful residents of HEADSPACE, and he is also the only character to have blank eyes with no pupils. His overall design stems from SUNNY's twelve-year-old appearance. Not much can be said about OMORI's personality, as he is a silent protagonist. However, it is implied that he is quite melancholic, as his narration sometimes has gloomy inputs and his final battle dialogue is directly talking down to SUNNY. His abilities are also reflective of this gloominess, being either violent in nature or simply gaining the SAD emotion, or having an advantage while SAD. However, it can be speculated that this is moreso reflective of SUNNY's emotional state, as OMORI is a character built from SUNNY'S conscience in WHITE SPACE and HEADSPACE.

KEL is one of the main three deuteragonists that join OMORI's party in OMORI. When tagged as the leader, KEL can throw various ball projectiles from certain platforms to hit objects otherwise inaccessible to the party. The HEADSPACE version of KEL appears as a young boy wearing a colorful tank top covered in multicolored squares. Like the others in the party, he does not wear socks or shoes and his hair and eyes are purple like AUBREY and HERO. During his youth, KEL is a bit bratty, impulsive and rude, always getting into little tiffs with his friends. He is very competitive by nature, always wanting to win games or races, and is indeed very energetic and fast. He also thinks romance is gross and that girls have cooties. However, even though he is loud and likes to annoy his friends, he genuinely cares about them to the point of constantly protecting them with a strong sense of justice.

AUBREY is one of the main three deuteragonists in OMORI that join OMORI's party. However, in the FARAWAY TOWN sections of the game, she serves as a minor antagonist. When tagged as the leader, AUBREY can smash obstacles with a bat. In HEADSPACE, AUBREY wears a light-blue dress and a pink bow in her long hair. As the other three, she does not wear socks or shoes and her hair and eyes are purple/dark blue like KEL and HERO. She also carries around a blue plushie known as MR. PLANTEGG. During her youth, AUBREY is very cheerful and is always happy to play with her friends. Always acting true to her feelings and strong-willed, AUBREY serves as a constant source of morale for her friends.This extends to often reminding the group of the right thing to do whenever they are distracted. Despite this, she becomes sad and worried quite easy, such as being the most anxious when BASIL goes missing. Often she is clumsy, resulting in yelling from KEL, who she always fights with.

HERO is one of the main three deuteragonists in OMORI that join OMORI's party. When tagged as the leader, HERO can use his charm to convince others to assist the party. The HEADSPACE version of HERO wears a set of blue-striped pajamas. His hair is unkempt from sleep, as seen in his sprites. Like KEL and AUBREY, he lacks socks or shoes and his hair and eyes are purple. According to SPROUT MOLE MIKE, he is 5'7" at the age of fifteen. HERO is also the oldest and tallest of the party. During his youth, HERO is the peacemaker of the group, who tries to restrain his friends whenever they get too worked up. He is described as having a mild personality and passionate in domestic work like baking, cooking, and cleaning, making him an ideal employee. HERO also has a charismatic side that he uses to charm others. He also appears to have arachnophobia (an irrational fear of spiders) to the point of freezing up completely. These traits are shared with his HEADSPACE counterpart.

BASIL is a major supporting character and the tritagonist in OMORI. He serves as one of the major driving forces behind the story's events as the party spends most of the game looking for him after his sudden disappearance. In HEADSPACE, BASIL is a medium-height boy with pale skin, teal eyes, mint green chin-length hair, and wears a purple-blue and pink flower crown. He wears knee-length denim overalls with a large pocket on the chest and a yellow button-up shirt under. He doesn't wear any shoes. BASIL is depicted as a relatively shy and socially anxious boy, well seen right after being introduced to the friend group, being very insecure and fearing of being perceived as a burden. He enjoys taking pictures, as his memories with his friends are his most treasured belonging, perceiving them as a way to permanently capture the moment.

? ? ?

SUNNY... don't worry.

Everything is going to be okay.