Honestly just read the novel it's really good!
I just finished the novel. Won't get into details, but you have been warned.
The relationship is interesting because of their dynamic, but the romance is very mild and doesn't really happen for a long time. The mushroom doesn't like the judge most of the time (I mean, he is a murderer and holds his life in his hands), but feels drawn to him and sympathetic. They do get together officially, but there are no explicit scenes, only a fade to black and vague description. For me, the romance became less interesting while the scifi aspects became more interesting as the story went on.
Are we gonna witness romantic moments between little mushroom and ML??? If yes how far in the story?? Please spoil me novel readers, and sorry for being so impatient