A gaku-dō is a hall where one hangs framed pictures or emas. Emas are blocks of wood usually on which one writes their wishes. In the Edo period, emas from famous artists would be displayed here along with songs and poems from famous poets. This place acted as a museum of sorts. There were also emas on which things like “I will quit drinking” or “No more women” were written. By hanging up such declarations in the gaku-dō for all to see, you can understand how it would make you more obliged to keep true to your resolutions.
Actually, there was another gaku-dō at this temple that burned down in a fire several decades ago. It used to be located near the pagoda. A donation from a kabuki actor, the gaku-dō had a sign hanging in front of it that read “Refreshment Area” where visitors would receive tea.
Furthermore, that kabuki actor presented a giant ema to the temple and people would come just to see the unusual ema. As a result, various other artists also wanted to display their art in the gaku-dō. From their point of view, if you had your artwork hung up in the gaku-dō, then it would be seen by many people and perhaps last there until the end of time. This place was the ultimate stage for art.
Before long, the gaku-dō became overfilled with emas, so a second was built, which is where you are standing now.