Torii gates are where a mage's education begins. They generate in the world like any other structure, and
/locate structure isekubed:torii_gate finds one.
Right-click a gate to learn DISCOVER, your first circle. A gate you find in the world also teaches one more word of its own. Different gates teach different words, so it is worth visiting more than one.
A found gate is fragile. Break any one of its blocks and the whole gate vanishes. You can also build a gate yourself. A built gate teaches DISCOVER but no word of its own.
Every gate has an offering barrel between its posts. The right offering, followed by a cast on the barrel, is answered. What a gate wants is for you to find out.