Shinpei's relationship with his friends evolves significantly throughout the series. At the beginning, Shinpei is somewhat distant from his friends and prefers to keep to himself. However, as the series progresses, he gradually opens up to them more, showing more vulnerability and forming deeper connections. His friends also learn more about his background and struggles, leading to a stronger bond and mutual support among the group. Overall, Shinpei's relationship with his friends transforms from surface-level interactions to a meaningful and supportive friendship as the series unfolds.