Characters page for the manga Inside Mari. Beware of unmarked spoilers!
- First-Name Basis: Refers to Mari and Yori by their given names, much to Yori's annoyance.
- Hikikomori: After he dropped out of college, he became a complete shut-in.
- Important Haircut: Cuts his hair after getting a part-time job.
- Loser Protagonist: He's a scraggly looking college drop-out who spends all his time indoors and has no friends or job. To make it worse, his parents don't know he dropped out and thus they're still supporting him. Subverted as he's not actually the protagonist.
- Man, I Feel Like a Woman: Subverted. He or really Mari under the belief that she's Isao, is completely horrified at the change and refuses to look at Mari's body.
- NEET: He has no job and dropped out of college in his first year. He later gets a job.
- Messy Hair: He has shaggy, unkept hair.
- Permastubble: Initially. He later shaves it off after getting a job.
- School Idol: Isao dreamed of becoming this in high school and college, however he was too introverted to even make friends.
- Screw Yourself: Isao-as-Mari masturbates Isao once. Subverted as there was no body-swap; Mari simply believes there was.
- Stalker with a Crush: He is in love with Mari and follows her around despite never even talking to her.
- All Periods Are PMS: Gets painful period cramps. This freaked out Isao when he first swapped bodies with her.
- Aloof Dark-Haired Girl: She's a tall, dark haired girl with long hair. Mari is popular at school but keeps even her friends at arms length.
- Break the Cutie: She was a Cheerful Child until her grandmother died and her mother changed her name. Afterwards she became more reclusive and stoic.
- Covert Pervert: She secretly buys porn magazines, more specifically the ones Isao sold to a local bookstore.
- Did Not Get the Girl: She and Yori part ways in the end.
- Do Not Call Me "Paul": Enforced by her mother. She changed Mari's name as a child to dissociate her from her paternal grandmother. Her birth name was "Fumiko".
- Dude Magnet: She attracts boys and men like bees to honey. Too bad for them that she has no interest in men.
- Empty Shell: Becomes catatonic after she triggers memories of her grandmother.
- Last-Name Basis: She refers to Yori as "Kakiguchi-san".
- Multi-Gendered Split Personalities: She has two female personalities and one male one based on Isao.
- Schoolgirl Lesbians: She's secretly a lesbian. She later develops feelings for Yori.
- School Idol: Everyone adores her at her school and she gets good grades.
- Stalker Without a Crush: She stalks Isao.
- Tomato in the Mirror: Mari has split personalities but doesn't realize it.
- Intergenerational Friendship: She's a high schooler who befriends a man a few years her senior. Subverted once The Reveal occurs that no body-swap happened, thus making them actually the same age.
- Last-Name Basis: She only refers Isao as "Komori".
- Schoolgirl Lesbians: She's in love with Mari.
- Sibling Yin-Yang: Is popular and sociable, unlike her sister Yori.
- Abusive Parents: Is emotionally distant and abusive towards Mari. She went as far as to change Mari's name because she hated it and the woman (her mother-in-law) who suggested it.
- Walking Spoiler: She isn't given characterization or a name until late in the manga. She is however a very important character in the longrun.