Grangold (グランゴルド Gurangorudo) is the kingdom of the Gold region of Sentora. It is said that this too is where humans and monsters coexist. However, unlike the Grand Noah Kingdom, the human citizens enforced slavery on the monsters and became sloths, letting their obedient servants do all the work for them.
When Luka first arrives in Grangold Castle, he is confronted by Golem Girl, the gatekeeper of the kingdom. Assuming that the Golem Girl was attacking Grangold, Luka breaks her, and is arrested by the castle’s soldiers.
Being released after a carrier pigeon from Ilias Village confirms his birth and parentage, Luka soon notices that, unlike Grand Noah, there are only a few types of monsters walking through the streets: Ant Girls and Mud Golem Girls, both busily working around.
Luka learns that the truth about the coexistence in Grangold is actually that Queen Ant is sealed in the basement of the castle, so the Ant Girls recognize humans orders as their queen orders, and do all the work in town, carrying things, working in the shops and acting as the local priest, even the Grangold King just goofs around all day while the Ant Girls take care of government affairs. The other monsters are artificially made, not having a will of their own: the Mud Golem Girls works mainly in engineering projects, and there are Automata Girls in the inn, created just to service clients.
Disappointed with the truth, Luka spends the night in the inn, refusing service from an Automata Girl but is "rewarded" with a blowjob from Alice. The next morning, the Ant Girls and the artificial monsters suddenly start attacking the citizens. Still disappointed with the actions of the people in town, Luka has the option of leaving Grangold, letting the citizens reap what they sow, but he can return later to help.
If he decides to help, Luka defeats a Mud Golem Girl and then an Automata Girl, but then realizes that fighting the rampaging monsters at random will be meaningless, and decides to go straight for the castle, where Queen Ant was supposed to be sealed. He encounters a trio of Ant Girls trying to secure the humans, but Luka manages to rescue them as the Grangold King leads them to escape. After a battle, the Queen Ant orders her followers to resume rounding up the humans and let her deal with Luka, not wanting to see her children harmed further.
Alice shortly appears and, wondering how the humans sealed Queen Ant, leads him to some hidden steps downward, where a magic engineer is trying to fix the machines. Alice hypnotizes her and forces her to reveal the truth: the technology of Grangold was given by Promestein, who wanted to test sealing powerful monsters so she could eventually seal the Monster Lord. Alice shortly leaves before the battle with Queen Ant.
Queen Ant soon appears, who refuses to stand down. Before Luka can deal the sealing blow, Alice returns, carrying the Grangold King. The Queen Ant recognizes the Monster Lord, but Alice quickly dismisses it as it is not important. The Grangold King apologizes and agrees to become the Queen Ant’s slave if she releases his people, stating that he originally believed that monsters were mindless creatures that could easily be ruled over. Luka and Alice also input their words and try to convince Queen Ant to stand down, seeing how her actions would be viewed by others. After a long talk, the two rulers shake hands and promise to end everything.
Realizing that the city’s reputation though the world was a lie, the King tells Luka that he intends to let monsters live there in harmony with the humans, turning the falsehood in a reality. He also reveals that Alice convinced him to take full responsibility over his people. The two rulers wish Luka and Alice well of their journey, although Alice seems a bit disappointed with the lack of a rewarding feast.
After Ilias launches her war against humanity, Spider Princess invades Grangold Castle with an army of spider monsters, but the Queen Ant and her Ant Girls stand against her. The Ant Queen condemns the Spider Princess for preying on humans, getting exiled from her hometown and dethroned as the Queen Insect before attacking her. However, Spider Princess summons her secret weapon: the artificial Fire Spirit Gigamander, proving herself more than a match for Queen Ant. She then commands all her minions to descend upon the castle and to consume everyone, resulting in a violent war between the castle guards and ant girls vs the spider monster army.
Later, Luka hears from a Tarantula Girl in Grand Noah that Spider Princess has requested all spiders to assemble, but some like her did not partake in it.
Luka eventually arrives at Grangold and assists in fighting against the spiders. Eventually, he manages to reach and defeat the Spider Princess, halting her ambitious goal and causing her minions to flee.
- The Grangold Castle theme is a sped-up version of La fille aux cheveux de lin by Claude Debussy.