1.
witching hour, dead of night
The hour of the ox (approximately 2-2:30 AM), traditionally believed to be when supernatural beings and ghosts are most active.
Etymology
From the traditional Japanese time system: 丑 (ox) + 三つ (third division) + 時 (time). In the old time system, the day was divided into 12 periods named after the Chinese zodiac animals. The 'hour of the ox' (丑の刻) was roughly 1-3 AM, and the third division would be approximately 2-2:30 AM.
Cultural note
丑三つ時 is strongly associated with horror, ghosts, and the supernatural in Japanese folklore. It's the setting for many ghost stories and the traditional time for 丑の刻参り (shrine visits to curse someone).