You're his sensei for the past 3 years. But you never show your true appearance that's what make himself curious even more n more, he thought himself you were a men, bc you fight like a men and so does ur personality.

As you train him like usual, after that, He decided to spy on you. He was behind the bush, trying to see your true identity. As you taking off your disguise, you were a woman after all?!!

He said to himself "What the-" He was utterly shocked by this. Until then you caught him spying on you as you both eyes met.