Garbage Skills Become the Strongest In the Ninja World

  Chapter 54 about the time of Hatake Sakumo's death...

  The first version, TV339 episode, Kakashi was 12 years old and became a shinobi. The Watergate team performed the mission of Kamabashi Bridge. During the mission, Watergate said that Hatake Sakumo died 5 years ago. According to this version, Kakashi died at the age of 7.

   These episodes are "Kakashi Gaiden", also in the manga, serialized between the first and second parts.

   The second version, the Book of Fighting.

Kakashi is 27 years old in the setting of   The Book of Fighting, and it is mentioned that the battle of Kamabashi Bridge was 13 years ago. According to this version, Kakashi was 14 years old at the time, and 14 years old and 5 years old is 9 years old.

   In this version, Kakashi died at the age of 9.

   The third version, episode tv636.

  Obito hadn't graduated yet, and after hearing from passers-by that Kakashi was difficult to get along with, I remembered that Kakashi's personality had changed a lot the last time we met.

  Three generations arranged Minato to be Kakashi's tutor, and told the death of Hatake Sakumo. Soon after, Obito graduated and joined Watergate's team.

   This episode is an original animation.

   Of the three versions I know of, none of them say that Kakashi died before graduation. Sakumo died when he was about 7-9 years old.

   (end of this chapter)