Naruto: I Can Become Stronger Just By Teaching.

Mu Yue found himself in the world of Naruto and became a regular Chunin teacher at the Ninja Academy in Konoha, but he was also a member of the Root Organization. Fortunately, he awakened a Teacher System, which allowed him to grow stronger through teaching. To avoid becoming a disposable pawn for Danzo, he diligently focused on teaching to enhance her abilities. "After completing teaching with an A rating for the first time, you receive a reward — Mastery in Fire-Style Chakra Nature Transformation." "Your guidance has helped Uchiha Shisui's thoughts mature, and he has learned independent thinking. You receive a reward — Sage Mode!" Under Mu Yue's guidance, Shisui realized that the village's enemies weren't necessarily from other nations; they could also exist within the village. Not everyone who spoke about the Will of Fire would actually act in accordance with it. Kakashi shook off the nickname of "low achiever" at the Ninja Academy, and Guy became a master of Taijutsu even earlier...