Since Maritzis was very interested in Nicole,
Han Dong simply "went with the flow" and handed Nicole over.
Firstly, it would allow Nicole to gain training,
Secondly, considering that Maritzis often clung to him—although the clinging was of a "looser" type that wasn't uncomfortable—it could still affect Han Dong's studies to some extent.
It wasn't easy to stay in Toad City for a while, and Han Dong wanted to take the opportunity to learn as much as he could.
...
Han Dong borrowed a "Encyclopedia of N'Kai" which had detailed summaries of the origins and creation of N'Kai, as well as the demon vassals that settled there.
Among them was a detailed classification and explanation of the direct line of relatives of N'Kai - the Toad Demons. (King-Level cities like N'Kai only categorized demons. Those below the demons were referred to as 'lower order,' 'offspring,' or 'lowly slaves' and were not divided into detailed categories.)