Doushu profoundly shapes Eigetsu's life, molding his philosophical outlook and personal struggles. As Eigetsu's mentor and guardian, Doushu instilled principles embodying a nearly Christian outlook, emphasizing moral integrity and self-sacrifice. This guidance anchors Eigetsu's character arc, fueling his sense of existing in a doomed state while striving to uphold the highest good learned from Doushu. Doushu's impact echoes through Eigetsu's interactions, particularly with Kourin. When Eigetsu withdraws emotionally, Ensei observes his preoccupation with personal things tied to Doushu's teachings, causing Kourin visible distress. Eigetsu openly admits avoiding relaxation to stay focused on obligations linked to Doushu, fearing he might otherwise forget the things that I have to do. This positions Doushu as a weighty responsibility Eigetsu feels compelled to honor, regardless of personal cost. The narrative directly frames Eigetsu's rejection of personal happiness as a consequence of Doushu's influence. His resolve to prioritize duty over relationships, leaving Kourin anxious and tearful, stems from commitment to ideals attributed to Doushu. Though Doushu's physical presence remains limited, his ethical framework propels Eigetsu's development, casting Doushu as a catalyst for themes of sacrifice and unattainable redemption.