Your rank as a ninja determines everything from your range of strength as well as which gaming features you have access to.
Max Stats by RankEdit
Academy Student is the starting rank when you join Ninja RPG. This rank is basically a way for you to train to increase your stamina and chakra to a point where you will be able to defend yourself in the higher ranks, as without the basics, becoming strong will never be accomplished. As you start to become strong, you start your journey to become a great ninja in your respective village or an international criminal. Main Article
After you reach max level Academy Student, 150 total combined defense, and 6 intelligence you can take the Genin exam to rank up. Genins have access to more features like D-rank missions, senseis, and bloodlines. Main Article
The requirements to rank up to Chuunin include one offense stat over 15k, the sum of your defenses over 15k, and each general over 630. Chuunins have can join ANBU squads, complete C-rank missions, attack other Chuunin and Jounin, can leave their village, and can marry another ninja. Main Article