竹宮惠子
Like Hesse's "Demian", "The Heart of Thomas" is a "Bildungsroman" about spiritual education during formative years. Welker writes that Juli's character arc of being unable to love, befriending Erich, and leaving the school environment of Schlotterbach is one that is consistent with a ""Bildungsroman" paradigm." Shamoon notes that unlike other manga works of the 1970s that feature male-male romance, "The Heart of Thomas" does not overtly depict sex; she argues that by depicting its characters maturing through spiritual and familial love rather than romantic and sexual love, "The Heart of Thomas" functions as a "transitional work" between "childish" "shōjo" narratives typical of the 1970s and earlier (such as "Paris–Tokyo" by Macoto Takahashi and "Candy Candy" by Kyoko Mizuki and Yumiko Igarashi, the latter of which Shamoon notes depicts "idealized romantic love in a heterosexual framework"), and "shōjo" manga from the mid-1970s and onward that targeted an older readership. Thorn similarly contrasts the focus on spiritual love in "The Heart of Thomas" to "Kaze to Ki no Uta" and the works of Keiko Takemiya, which focus primarily on physical love.