Well, 'elceed light novel' could potentially have a plot centered around a young protagonist. They might be on a journey to achieve a certain goal, perhaps related to power or knowledge. Maybe there are different factions or groups in the story that the main character has to interact with, and through these interactions, the plot unfolds. There could be challenges, both physical and mental, that the character has to overcome, and these form the core of the story's development.
I'm not familiar with the 'elceed light novel' so I can't name the main characters. However, in a typical light novel, the main characters could range from a young and plucky hero or heroine with a big dream, to a more experienced and wise figure who guides the younger ones. There might also be antagonists, characters who oppose the main character's goals and create conflict in the story. Without reading the novel, it's just speculation based on common light novel tropes.
I think Christmas piano cartoons that have a heartwarming story behind the music tend to be well-liked. Maybe like a group of friends coming together to play piano for a charity event during Christmas. Also, ones with colorful and magical settings can attract a lot of viewers.
You could have them constantly trying and failing at diets or exercise routines in a hilarious way. Or maybe they have a love for food that leads to funny situations. Another option is to have other characters' reactions to them be funny, like being overly shocked or scared of their size.