Masa originally trained as a busshi, a Buddha carver, and in this tradition there is an idea that there is a spirit residing within every tree, and the task of a carver was simply to recognize the spirit and carve out its form from the tree in the shape of a Buddha. As a sculptor working with wood, a natural material, his relationship with his material represents the relationship between humans and nature, and the integrity which should exist within that relationship. This is an issue that he has been contemplating, particularly since the tsunami and the accident at the nuclear power station in Fukushima. Looking around at modern life both in Japan and in the UK, he realises how much humans have lost their connection with nature, along with the respect and fear of natural forces, and this is an issue he would like to explore through his work.

This has led him to the ancient practice of tachigi-bori, literally translated as 'standing tree carving', which is the traditional Japanese practice of carving sculptures into living trees. The practice is linked with the Shinto belief in the sacred force that resides in all things and is a particularly powerful presence in any large old tree. The carving gives a form to the spirit of the tree, and the artist works with the living tree to avoid damage and accepts the changes that the living tree contributes to the image.