Oku is often associated with the concept of ma, which corresponds to the notion of "in-between" Oku has literal meanings for private, intimate, and deep. sacred too.  

The Japanese concept of Ma is a pause in time, an interval or emptiness in space. Ma is the time and space life needs to breathe, feel and connect. If we have no time, if our space is restricted, we cannot grow. This universal principle applies to every aspect of life. In that stillness, free of noise, we connect on a soul level.