One idea could be to cross it with a fantasy world like 'The Lord of the Rings'. The characters from Akama ga Kill could be inserted into Middle - earth, facing new challenges and forming alliances with the races there. For example, Tatsumi could learn new combat skills from the elves.
To start, do a lot of research on both Akama ga Kill and the other franchise. If it's a crossover with a superhero universe like the Marvel Cinematic Universe, understand the powers and personalities of the superheroes. Then, create an interesting opening scene. It could be a strange event that pulls the Akama ga Kill characters into the new universe, like a mysterious portal opening up and sucking them in.
Akame ga Kill novel's plot is centered around the struggle between Night Raid and the corrupt powers. Night Raid is a group of assassins. Tatsumi's entry into this world of conflict is a significant part of the story. As the story progresses, the battles become more and more fierce. The relationship between different characters, such as the complex feelings between Tatsumi and Esdeath, also adds depth to the overall plot. There are also political intrigues and power struggles within the government that Night Raid is trying to overthrow, which makes the plot very engaging.
The manga of Akame Ga Kill is filled with intense action, complex character developments, and a story of rebellion against a corrupt empire. There are many battles, plot twists, and emotional moments.
The Akame ga Kill manga ran for quite a while. But the exact number of chapters and volumes might vary depending on how you count and which editions you look at.