deep inside; innermost place
secret techniques (of an art or skill); inner mysteries; essence; quintessence; heart
depths; deep place; bottom (of one's heart)
interior; backwoods; hinterland; back regions
esoteric doctrines; mysteries
Ōu (the two former provinces of Mutsu and Dewa); Tōhoku
esoteric writings; Upanishad (sacred Hindu treatises)
one's heart of hearts; the depths of one's mind
secret knowledge; interior of a temple
inner mysteries (of a field of study); secrets
deep truth; deep knowledge
secrets; mysteries; secret formula; essence; esoterica (of an art, martial arts, etc.)
Rikuō (former province located in parts of present-day Aomori and Iwate prefectures)