Gateways (トビラ, Toriba) are a key object in both Suikoden Tierkreis and Genso Suikoden Tierkreis Hoshikuzu no Shiro. Gateways connect to the Corridor, allowing individuals to traverse the Infinity.
Gateways were the point of contact for the Corridor which connected the Infinity, allowing people to travel to other worlds.
One simply passed through the Gateway and then exited through a different Gateway to enter another world. There were few restrictions on Gateway travel. For example, a person was able to travel to another location in the same world by using Gateways that connected to two different points in the same world.
However, its major restriction was that when returning to your original starting point, you must use the Gateway you originally took, otherwise it was impossible to continue traveling. Thus, if your original Gateway was lost, destroyed, or buried, you would be unable to traverse the Infinity using a Gateway. If a Gateway survived a process such as world fusion, however, it would still function as normal.
After the One King was destroyed, the Gateways ceased to connect to the rest of the Infinity, indicating that the One King's existence played some role in connecting the devices. Following this, it was impossible to go back and forth between worlds.
- Genso Suikoden Kiwami Encyclopedia, page 751