Kakashi tattoo means to work hard and never give up. Kakashi, even in the entire history of Naruto animation, is a popular character. He not only appears early, but also is a strong man in the end. Kakashi's strength lies in the Ninja with unique skills. It can be said that in the early story, he is a particularly important person with this strength.
Throughout Kakashi's life, he experienced darkness and helplessness, but he finally succeeded in the last time. Looking at the seventh class led by him, it seems that he saw them once led by Watergate. Kakashi has always expressed the belief that "no matter what he has experienced, he will not give up." just like many people today, no matter what hardships he has experienced, he is still struggling the next day.
Source: @o.didasart