The author noted that the character of Lavi was popular with fans, placing third in a poll (behind Allen and Kanda) despite infrequent appearances in later story arcs, and she promised that Lavi would return. The story arc involving Alma Karma, featuring several characters, was difficult for the author; as a result, the next arc in which Allen leaves the Black Order contained fewer characters per chapter due to its different format. The character of Apocryphos was introduced to hint at the Heart, a plot element briefly described in a past storyline which would later reappear. Due to "Jump Square" (the manga's magazine at the time) readership—older men, rather than children—Hoshino found Allen the most difficult character to write. She does not want Allen's problems in recent story arcs to lead to portraying him as a troubled teenager, preferring to show him as a cheerful person with a balance of strength and sorrow. After "D.Gray-man" dark narrative, Hoshino plans to write more lighthearted series in the future.