Masachika Kumeno

Masachika Kumeno was a Demon Slayer acquainted with Sanemi Shinazugawa.

History
Little is known about Masachika prior to joining the Demon Killing Corps, but he had a younger brother killed by demons.

After Sanemi began wandering in search of demons to kill, he met Masachika by chance. Masachika was already a member of the Demon Killing Corps, and he arranged a trainer for Sanemi so he could properly learn how to defeat demons. The two challenged and successfully defeated the previous Lower Moon One of the Twelve Demon Moons, but Masachika perished in the conflict.

Sanemi rose to the position of Wind Pillar alone, bitter over Masachika's death. When he confronts Kagaya Ubuyashiki about the latter's inability to fight, Kagaya identifies Masachika by name, much to Sanemi's surprise. Kanae Kocho then informs him that Kagaya has memorized every slain demon slayer's name and background, and Kagaya decides to give Sanemi Masachika's will.

Sanemi Shinazugawa
Sanemi and Masachika had a close brotherly relationship, and Masachika viewed Sanemi as the younger brother he lost.