Yōkobo is a behavioural object designed by a multidisciplinary research team to strengthen the connection between retired couples living at home. As a research artefact, Yōkobo is at the crossroads of a sensitive approach and a robotic trend that bridges the gap between humans (Human-Robot-Human Interactions field). This work follows a user-centred design approach spread over three phases. Following field studies regarding newly retired couples, the first phase aimed to identify an experience concept to strengthen the bond within the couple. In the second phase, the team worked on defining the form of the behavioural object, the associated services, and the interaction modalities of this behavioural object. In the third phase, the roboticists implemented a functional prototype used in several studies and explorations.