Another few months pass by, the war against Monster Overlord is prolonged. The reason is the mobility of 7th-grade combatants. To safely fight against Monster Overlord at least need two seventh-grade combatants. Another one needs to successfully kill it.
This means it needs at least three big nations to work together to kill the Monster Overlord. However, there are still countless high-grade monsters and undead monsters which need at least another two seventh-grade combatants to keep them at bay.
In total, they need at least five-nation leaders or seven grade combatants to fight against the Monster Overlord army. Even the elf race didn't have such a power to handle all of this alone.
Since the last Monster Overlord attack, most of the big nations have had internal problems that cause some instability in their nations. Some of them even in the state of civil war. Furthermore, there is an economic crisis that has plagued all over the nations.