The Northern Seas (北の海 Kita no umi) are a location in Monster Girl Quest. They surround the Gold region of Sentora. Not far from Gold Port, these waters are ruled over by Poseidoness, guardian of the Silver Orb. It is also where Captain Selene’s Ship is found, just about a week traveling length from Gold Port. These waters are notably more dangerous than the Southern Seas, as they are much closer to Hellgondo.
After Alice informs Luka of the purpose of the Silver Orb, Luka sets out to find it. He enters the Northern Seas and encounters and defeats a Dagon. He eventually reaches the Northern Sea Temple and meets Poseidoness. The powerful monster accuses him of a thief and attacks him. After a fight, Poseidoness stops and reveals that she was actually testing him, having already been told of him by Kraken. She hands over the Silver Orb.
Luka later sets sail with the ghost of the famed pirate Selene through the Northern Seas to her deserted ship. Here he fights the Beelzebubs, ancient fly monsters that Selene had accidentally released long ago, and defeats them with Alice's help. They obtain the Purple Orb and bring peace to Selene’s and her crew’s spirits.