https://e621.net/posts/2513871?q=zero-sum
- https://static1.e621.net/data/80/e6/80e6475302668c024cd3f52c22ef0edd.webm
https://static1.e621.net/data/c9/50/c95083e2dd8aec3823ba4b77e77195e0.webm
FULL-https://static1.e621.net/data/85/80/858085c264ebec3e93c2383b3b1e0619.webm
FULL-https://static1.e621.net/data/c7/10/c710bbfc027ac479cc7f507fa711cad1.webm