Masachika Kumeno

thumb|Masachika's lively and cheery demeanor, in contrast to Sanemi's character. Masachika was a very kind person, befriending Sanemi and even introducing him to someone who could help train him. In stark contrast to Sanemi's ill-tempered and rude behavior, Masachika is also shown to have a jolly and high-spirited personality. He frequently teased Sanemi by inviting him to eat out, imploring him to view him as his big brother, and poking fun at Sanemi's recklessness and cluelessness to romance. Masachika was also very sociable and charismatic, telling Shinobu Kocho a humorous tale about Gyomei Himejima being chased for playing the flute too loud and fondness for cats, and endearing himself to a grumpy old man with his exuberant charm, making the man retell the story of "Yae". Despite his usual playfulness, he has a serious side as a Demon Slayer, as he was absolutely repulsed upon learning that as a human, Ubume had tortured and killed her daughter, and became full of rage when the demon made facetious excuses over her prior actions. His anger was further stirred when Ubume correctly analyzed that Sanemi was a victim of parental abuse and feigned pity for him. In his final moments, Masachika's kindness caused him to lose focus when one of Ubume's kidnapping victims attempted to defend the demon, leading him to be fatally struck by Ubume. Despite this, Masachika still showed concern for the girl and Ubume's other victims when the demon was defeated. His last words to Sanemi were telling the Demon Slayer to be happy and live on. In his will, Masachika considered Sanemi as a brother and wished the best for his loved ones.

Masachika was a young man with an average build and short, spiky black hair. He had noticeably small, rounded eyebrows and two prominent scars on his left cheek. His mouth was usually curved into a happy smile. Masachika wore the standard Demon Slayer uniform that consisted of a dark gakuran jacket, white belt, and baggy hakama pants tucked into white wraps of cloth around his ankles. In Kimetsu Gakuen!, his eyes are olive green with white diamond-shaped pupils.

Overall Abilities: Masachika was an incredibly powerful swordsman, who attained the position of Kinoe, the highest non-Hashira rank in the Demon Slayer Corps. He and Sanemi, who was also Kinoe at the time, were able to successfully defeat Lower Rank One Ubume, the most powerful of the Lower Ranks despite sacrificing his life in the process.