If you don't like romance and harem novels, then this list might help you find good novels.  This list of Japanese novels is generally of the SOL, fantasy, and adventure genres with the theme of family and friendship.  

For example, the adventures of a father and his daughter in a fantasy world.  Or it could be SOL's story that warms the heart.  

Apart from avoiding the harem and romance genres, I also try to avoid red genres as much as possible (genres are forbidden or should not be read by children or under 15 years old) such as adult, mature, ecchi, and gore. But it could be that in the story there is some content as subplots even though it is not the focus of the story. I mean, I'm also disturbed or uncomfortable with the existence of the red genres or similar contents, even though sometimes the contents are a little needed for plot story development.

The following are recommendations for Japanese novels without romance and harem but focusing on stories of family and friendship in a fantasy world. I hope that you all enjoy reading these novels!