the six realms (Deva realm, Asura realm, Human realm, Animal realm, Hungry Ghost realm, Naraka realm)
the six historical styles of writing kanji: large seal, small seal, clerical, triangular-swept clerical, running, and cursive
the Six Kingdoms (of China's Warring States period: Qi, Chu, Yan, Han, Wei and Zhao); the six tree-derived incense varieties used in kōdō ceremonies
Six Dynasties (of China: Eastern Wu, Eastern Jin, Song, Qi, Liang, Chen); calligraphic style of the Six Dynasties period
six forms of the Shi Jing (genre: folk song, festal song, hymn; style: narrative, explicit comparison, implicit comparison); six forms of waka (allegorical, enumerative, metaphorical, allusive, plain, congratulatory); six principles of calligraphy; six classes of kanji characters
The Six Secret Teachings and The Three Strategies of Huang Shigong (two ancient Chinese military treatises); secrets (of the art of war, etc.); mysteries
six ministries (of Zhou dynasty China)
the six classes of Chinese characters; the six historical styles of writing Chinese characters; Hexateuch (first six books of the Hebrew Bible)
yin, yang, wind, rain, darkness, light; cold, heat, dryness, dampness, wind, fire; six emotions (joy, anger, sorrow, pleasure, love, hate)
Six Ministries (in Sui dynasty to Qing dynasty China)
six ministers (of the six Zhou dynasty Chinese ministries)