perpetual calendar for auspicious/inauspicious days
A traditional Japanese calendar used to determine lucky and unlucky days for events such as weddings, funerals, and travel. Often consulted for 六曜 (rokuyō) and other fortune-telling purposes.
My mother was consulting a perpetual calendar to choose the wedding date.
万年 (ten thousand years, eternity) + 暦 (calendar). The term suggests a calendar that can be used perpetually, as the cycle of days repeats.