One idea could be a crossover where Naruto characters visit the world of Maken Ki. For example, Naruto and his friends could be on a mission that accidentally transports them to the Maken Ki universe. They might have to team up with the Maken Ki characters to face a common enemy that threatens both worlds.
The main characteristics of 'Maken Ki Sex Manga' include provocative themes, detailed illustrations of intimate scenes, and a focus on adult fantasy. However, such content may be controversial and against certain moral standards.
I'm not entirely sure specifically as there could be various themes in 'Maken - Ki' light novel. It might involve elements like action, adventure, and unique characters in a fictional setting.
One common theme could be forbidden love. Since it's a lemon fanfic, there might be a sense of the relationship being something that is not allowed or is against some sort of norm in the original story.
One common theme is power - up. For example, in a crossover with a battle - focused series, the characters from Maken - Ki might gain new powers or abilities. Another theme is relationship building. When crossed over with another series, new friendships or romances can be explored between the characters of Maken - Ki and those from the other work.
You might try looking on some specialized manga websites or forums. But be careful, as accessing uncensored content from unauthorized sources could be illegal.
I'm not sure specifically which 'maken ki lemon fanfic' you are referring to. There are many fanfic platforms out there like Archive of Our Own (AO3) where you might be able to find relevant works. You can try searching for it using the tags related to 'maken ki' on such platforms.