Obaku Zen is a unique school of Zen Buddhism that originated in China and was later introduced to Japan in the 17th century. It is a blend of Zen with Pure Land elements, incorporating both meditation and devotional practices. The main texts or scriptures used in Obaku Zen are the Three Pure Land Sutras, the Platform Sutra, and the Diamond Sutra.

The Three Pure Land Sutras, also known as the Three Pure Land Classics, are the foundational texts of Pure Land Buddhism. These sutras describe the Pure Land, a realm of enlightenment presided over by the Buddha Amitabha, and teach devotees how to reach this realm after death. In Obaku Zen, these sutras are used to cultivate faith and devotion in the Pure Land and Amitabha Buddha.

The Platform Sutra, also known as the Sutra of the Sixth Patriarch, is a key text in the Ch'an (Zen) tradition. It documents the teachings and life of the Sixth Patriarch, Huineng, who is considered the founder of the Southern School of Ch'an. This sutra emphasizes the importance of direct realization and the inherent Buddha-nature in all beings. In Obaku Zen, the Platform Sutra is used to guide practitioners in their meditation practice and to deepen their understanding of the nature of reality.

The Diamond Sutra, also known as the Vajracchedikā Prajñāpāramitā Sutra, is a Mahayana Buddhist text that is highly revered in the Zen tradition. It is considered to be one of the most profound and influential sutras in Buddhism, teaching the concept of emptiness and the non-dual nature of reality. In Obaku Zen, the Diamond Sutra is used to guide practitioners in their understanding of emptiness and to transcend dualistic thinking.

In addition to these main texts, Obaku Zen also incorporates other sutras and teachings from both the Zen and Pure Land traditions. This blend of texts and practices allows for a comprehensive approach to spiritual development, incorporating both meditation and devotion.

In conclusion, the main texts used in Obaku Zen are the Three Pure Land Sutras, the Platform Sutra, and the Diamond Sutra. These texts are essential in guiding practitioners towards enlightenment and deepening their understanding of Zen and Pure Land teachings. By incorporating these scriptures into their practice, Obaku Zen practitioners are able to cultivate faith, wisdom, and compassion in their spiritual journey towards awakening.