This Torii icon is made in Material Design style developed by Google. This style is based on extremely simplified shapes, thin two-pixel lines, and is optimized for 24x24 px. Unlike other vector icon packs that have merely hundreds of icons, this icon pack contains 4,300 icons, all in the same style and quality.
It looks like an entrance to a gateway, like a tree fort, except without the ladder. It looks like the letter H in the English alphabet. It has two stumps, or poles with a roof on top. There is also a similar shaped pole running horizontal to the two poles.