The following description comes from the event organizer.
Moonviewing, or O-Tsukimi in Japanese, is the custom of gazing at the full moon and enjoying its sacred beauty. Portland Japanese Garden schedules this beloved annual tradition to coincide with the harvest moon, which occurs anytime from September to early October.
During Moonviewing, people gather to appreciate the moon’s beauty and pray for good fortune and an abundant harvest. At this festival, one of the most beloved at the Garden, guests anticipate the moonrise with a cup of tea and an opportunity to compose haiku as shakuhachi and koto music wafts through the air.