This is the interior renovation of the existing house in Tokyo designed for accommodating 4 generations of family members. The house was built approximately 40 years ago. While the daily behaviour patterns of the family members is different, creating a space to promote connection between all generations was a major focus. Also, it was essential to improve the quality of the interaction of space and enhancement of introduction of natural daylight and ventilation into spaces. Having above in mind, the shared spaces were designed in each floor to promote the connection of the generations, and each space was carefully arranged in accordance with the existing widows to take full advantage of daylight and ventilation At the same time, the reinforcement and optimization of the existing structure were studied. As a result, some columns were deemed redundant and removed - providing an opportunity to create flexible open spaces. The ceiling of the shared space on the second floor is catenary shaped - enhancing a natural connection to the outside and maximizing the diffusion of the daylight. This ceiling gently envelopes all 4 generations who ultimately enjoy living in a space abundant of natural daylight and ventilation.