In Vajrayana Buddhism, the Womb Realm (Sanskrit: garbhakoṣadhātu, Japanese: 胎蔵界 taizōkai) is the metaphysical space inhabited by the Five Compassion Buddhas. The Womb Realm is based on the Mahavairocana Tantra. The name of the mandala derives from chapter 2 of the sutra, where it is said that the buddha Mahāvairocana revealed the mandala's secret teachings to his disciple Vajrasattva from his "womb of compassion". In other translations, the term Matrix Realm or Matrix Mandala are used.
The Womb Realm is a very popular subject for mandalas, and along with the Diamond Realm (vajradhātu) Mandala forms the Mandala of the Two Realms. This mandala, along with the Diamond Realm, form the core of Japanese Tendai and Shingon Buddhist rituals, including abhisheka "initiation". In this ritual, new initiates are blindfolded and asked to toss a flower upon a mandala. Where the flower lands helps decide which Buddhist figure the student should devote themselves to.
In traditional Shingon halls, the Womb Realm Mandala is hung on the east wall, symbolizing the young stage of Mahāvairocana.In this setting, the Diamond Realm Mandala is hung on the west wall symbolizing the final realization of Mahāvairocana.
Dainichi is depicted in regal attire wearing a jewelled crown in the center of an eight-petaled lotus. Four Buddhas, representing the four directions, are depicted directly above, below, left, and right of Dainichi. The Buddha of the East, Hōdō, is illustrated on the top, the Buddha of the South, Kaifukeō to the right, the Buddha of the West, Amida, to the bottom, and the Buddha of the North, Tenkuraion, to the right. Four bodhisattvas, Fugen, Monju, Kannon, and Miroku, are illustrated between the Buddhas.
Four vases containing a lotus and a three-pronged Vajra, are placed at the corners of the Center Hall. The hall is marked off by a five-colored boundary path with each color referring to one of the five buddhas, knowledges, directions, roots, conversions, syllables, elements, and forms.