Katsura Hoshino's "Zone" one shot featured many similar characters, especially Allen Walker, the Earl, Lenalee, and General Cross. Many other characters are also "leftovers" from previous, and sometimes unpublished works. Allen Walker, the series' main character is also based on the previous series' protagonist, who is a girl. Hoshino changed some of his characteristics to make him look more masculine. Hoshino says that she does not know where Allen's concept came from, since she likes her main characters to be rambunctious, rude idiots. Nevertheless, the character started behaving more informally across the series. In addition, Lavi was meant to be the protagonist of one of her planned series, "Book-man". Other characters such as The Millennium Earl, Lenalee Lee and Komui Lee are based on real people, although Hoshino has not confirmed who they are. She has mentioned that some of them are famous scientists, while Komui is based on her boss. The character of Yu Kanda, based on a samurai, was created to vary "D.Gray-man"s Western setting. Hoshino found the design of some characters difficult early in the series. This resulted in Kanda having few appearances in the early volumes until the Noah's ark story arc, where he returned to join the cast with Allen having become harder to draw than him. On the other hand, she found the Millennium Earl and Reever Willingham easier to draw.