"I know how unfair the world is. . . because good people. . . die one after another." Masachika was Sanemi's close friend and colleagues in the Demon Slayer Corps. He saved Sanemi from a demon attack and healed his wounds. They soon found a brother like friendship within one another. Unfortunately, Kumeno would end up killed in a battle against Lower Rank One, Ubume. Sanemi, still grieving his death, even lashed out at Kagaya for thinking he would send Demon Slayers to their deaths haplessly.