Yumikage has long blond hair tied into a ponytail. He has dark sharp, blue eyes and is rather tall. He is seen mostly in his C3 uniform, like many other C3 employees. He wears a blue shirt under his jacket.
Yumi mostly seems to be a hard character who doesn't really empathize with others. When he, Tsurugi and Jun first appeared (in the manga) he behaved like the leader of their group - and seemed to be accepted as such.
He seems to be obsessed with the wish to eliminate Tsubaki. Even when Tsurugi is hurt, he still orders him to defeat Tsubaki. After the fight, Yumi says that Jun (who takes care of Tsurugi's wounds) spoils him too much.
Although he mostly seems harsh and aggressive, he seems to care for Tsurugi and really doesn't want him to get destroyed by Toma. He's often thought of as Tsurugi's mother or guardian by other characters.
Yumi is ashamed about his past - as he was forced to do cross-dressing in order to be a decoy for vampires.
When Yumi threatens someone, he usually threatens with "kind" things like "I'm going to embrace you!". He could also be some kind of Tsundere character. He also has childish attitudes, he has fun in teasing Jun, alongside Tsurugi.
Not much is known about his past, he used to attend the same school as Tetsu Sendagaya. It is also revealed that he comes from a family of mages. When he was a child, he was once saved by Tsurugi and Toma while he was being chased by vampires. Yumikage's family is apparently very wealthy.
- Shotguns: Yumikage's main magic tool and weapon are his pair of single shotguns. They most likely shoot artificial sunlight which is able to kill subclasses.
- Cry For The Moon: This spell is able to transform his shotguns into a black ball of energy, which then turns white. Yumikage is able to shoot destructive beams out of it. The more he shoots, the more the ball goes back to black, symbolizing how much of its power he has used up. After it's completely gone back to black it disappears and Yumikage falls asleep for a while. It's shown to be hard to control.
- Strength: 5/10
- Tactics: 9/10
- Cooperativeness: 4/10
- Mental: 4/10
- Appearance: 7/10
- Bad Language: 9/10
- "This is the end for you..." (Chapter 39, to Tsubaki)
- Yo, long time no see. Same brawn over brains as always, eh, Tetsu?" (Chapter 40, to Tetsu)
- "You know... We are not your 'friends.' This is just our job. Whether we cooperate with you or not is up to the organization." (Chapter 40, to Mahiru)
- "Well, he can't help it. He was bought by a bad old man when he was young." (Chapter 41, about Tsurugi, while drunk)
- "Really? You're Toma's slave, aren't you?" (Chapter 41, to Tsurugi)
- His favourite food is cheese risotto.
- His favourite drink is wine.
- His favourite color is citrus yellow.
- When he is drunk, he uses Junichiro to pick him up and carry him into his bed.
- He threatens people with doing nice things (If you do that, I'll hug you!).
- He has been known to cross dress in both his childhood and adulthood.
- Traditionally, Yumi's family dresses boys in feminine clothing until the age of 7 in an attempt to trick demons.
- Yumikage's elder sibling, Miyako, seems to have carried on with this tradition despite being an adult; Miyako refers to themself as Yumikage's older sister (to Yumi's apparent confusion) but at the same time says they're the husband of Tetsu's older sister (and is therefore implied to be a male who enjoys cross-dressing).
- When he was a child, he had black hair.
- Yumikage's code name within C3 is Hodur.
- It's revealed, that he was in love with Shifumi (Junichiro's late wife) but he didn't do anything to prevent her wedding with Junichiro and kept his love a secret (yet, Tsurugi seemed to know about it).
- His username on Servamphoto (a parody of Instagram) is cryforthemoon.