Nowadays, mobile instant messaging (MIM) is a necessity for our private and public lives, but it has also been the cause stress of In South Korea, MIM stress has become a serious social problem. To understand this stress, we conducted four focus groups with 20 participants under MIM stress. We initially discovered that MIM stress relates to how people perceive the territory in MIM. We then applied proxemics the theory of human use of space to the thematic analysis as the rationale. The data revealed two main themes: too close and too crowded. The participants were stressed due to design features that let strangers or crowds into their MIM applications and forced them to interact and share their status with them. Based on this finding, we propose a set of implications for designing anti-stress MIM applications.