the sixth hour of the morning; around 6 a.m. (in the traditional Japanese time system)
Refers to the sixth 'hour' (六つ) of the day in the old Japanese temporal hour system, which began at dawn. 明け六つ specifically marks the hour around sunrise, roughly equivalent to 6 a.m. in modern time. Used historically; now encountered mainly in literature, historical contexts, or explanations of the old time system.
In the Edo period, the bell rang at the sixth hour of the morning.
Around the sixth hour of the morning, the traveler left the inn.
Formed from 明け “dawn” and 六つ, the traditional time designation associated with the morning sixth hour. Under the seasonal temporal-hour system its clock time varied, though it was conventionally around six in the morning.