Osamu Mikumo is quite popular. His growth as a character in the original series makes him a great focus in fanfiction. He can be written in various scenarios where he overcomes more challenges. Yuuma Kuga is also popular as his unique abilities and his mysterious past offer a lot of room for exploration in fanfiction.
There is also Yuma Kuga. He is a very strong and unique character with special abilities. His combat skills and his background play important roles in the story development. He is from outside the world as we know it in the context of the novel, which makes his character full of mystery and interest.
If it's a crossover with a Naruto - like ninja world, Naruto himself would be a great addition. His energy and determination could contrast and complement the World Trigger characters. Also, Sasuke with his powerful ninja skills could add an interesting dynamic. In a crossover with a One Piece world, Luffy would be a fun character to include. His carefree yet strong - willed nature would bring a new flavor to the story.
Well, if we consider other shonen - style series, someone like Naruto from 'Naruto' could be a potential crossover character. His ninja skills and strong will could create some interesting dynamics with the 'world trigger' characters.
The unique world - building makes 'world trigger novel' interesting. It has a distinct setting with the concept of the Neighbors and the Trigger system.
The 'world trigger visual novel' probably delves deeper into the backstories of the characters in the World Trigger universe. For example, it might explore how the agents of Border came to be, their training, and their personal struggles. It could also provide more details about the Neighbors, their culture, and their motives for invading Earth. It offers fans a chance to experience the story from a different perspective, with different narrative choices and paths.