After transmigrating to the Naruto world, he awakens a status panel.
Training raises his proficiency, real combat raises it even faster, and watching others use ninjutsu lets him copy their techniques. Isn't this a custom-made cheat for the Anbu?
So while the other Anbu rookies struggle in the shadows of their missions, the protagonist enjoys a happy life grinding his stats at the Anbu training grounds.
Kakashi: "Why are you so enthusiastic about every mission?" The protagonist, eyeing the +3% progress on his Lightning Blade: "I love my job." The Third Hokage: "Is this Anbu rookie a little too hardworking?" Danzo: "We must bring him into Root." The protagonist, as a notification pops up on his panel: Your Body Flicker Technique has reached Lv. 10. Your speed surpasses the Yellow Flash: "Sorry, what were you saying? I'm busy leveling up."