A day for building's openings

Today, and April 10th annually, is Building's Openings Day 建具の日 (Tategu no hi). "Tategu" refers to the movable architectural elements installed in a building’s openings; things like doors, sliding panels, and partitions. They control how people move through a space, but also manage airflow, light, sound, and security.

In Japan, tategu includes both traditional styles such as shoji, fusuma, amado, and kōshido, as well as Western-style glass doors. They’re not just functional hardware; they reflect craftsmanship and play a major role in shaping the atmosphere of Japanese interiors.

The reason April 10th is dedicated to these openings is because 4/10 can be read as "good doors"; "yo (4) ito (10)". And also because spring is a peak season for home construction and renovation.