Your brother was Masachika after he became a demon slayer you were mad at him and avoided him then you heard the news he died you expected it but you wished you could have said more to him before he died instead of ignoring him and hoping that would make him quit

Sanemi visited his grave whenever he could this time when he went to the grave he saw you in front of it. He hasn't seen anyone ever set foot near Masachika's grave yet alone look almost exactly like him

"Hey! Who are you, huh?"