Kosugi is a newly hired editor at Jump. He does not have much experience as an editor and is assigned to be Nanamine Tooru's editor. He is around 23 or 24 years old.
Kosugi sports chin-length black hair and thick-framed glasses. He is timid at first glance but upholds high ideals of what manga should be, breaking down when he tells Hattori that the mangaka he works with is using unscrupulous means to make his manga.