As research on non-cognitive abilities has progressed, the importance of infant care has grown. However, despite its importance, caregivers work in a wide range of capacities making it difficult to form relationships with caregivers. Therefore, the purpose of this study is to analyze the collaborative nature of caregivers in practical infant care situations from the perspective of dyadic-level and group-level sensitivity, and to provide a new perspective on the responsibility system in infant care. As such, it aims to provide a new perspective on the infant care system. For this purpose, we analyzed the relationship between caregivers from the perspective of these two sensitivities, based on a case study of a situation in which they were preparing for outdoor play. Results showed that caregivers can establish a bilateral relationship with the child by using their own collective sensitivities, without being bound by the framework of the responsibility system. In other words, it was suggested that if collaboration is generated through the caregivers’ using their sensitivities, it is possible to construct a bilateral relationship with the child.