Boruto - I think it's because Kakashi is a super talented ninja and he's just naturally gifted with youthful looks. It must be some kind of special jutsu or genetic advantage. Sarada - I have heard that Kakashi has a Sharingan, which is a powerful eye technique. Maybe that has something to do with his youthful appearance. It wouldn't be surprising, considering how many other Sharingan users have unique abilities. Mitsuki - Kakashi-sensei is known for being a master of various jutsu. Perhaps he has learned some kind of secret technique that keeps him looking young. It would make sense, given his experience in battle. Shikadai - I think Kakashi just takes really good care of himself. He's always been a disciplined ninja, so it wouldn't be a surprise if he has some kind of special regimen that helps him stay young. Inojin - Maybe Kakashi-sensei has found some kind of mystical fountain of youth. It sounds crazy, but in the world of shinobi, anything is possible. Chocho - Kakashi-sensei is so cool and stylish, maybe his fashion choices have something to do with it. Dressing well can make you look younger, you know! Metal Lee - I've heard that Kakashi-sensei is extremely dedicated to his physical training. Maybe his rigorous exercise routine is the secret to his eternal youth. Sumire - Well, Naruto is the Hokage, and Kakashi was the previous Hokage. Maybe being in positions of leadership keeps them feeling young and energized. Denki - Kakashi-sensei is a legendary ninja, so it's possible he has access to some kind of forbidden jutsu that slows down the aging process. Iwabe - Kakashi-sensei is a genius tactician, so maybe the stress of constantly strategizing and leading missions keeps him young. Stress can do strange things to the body, after all. Namida - I think Kakashi-sensei just has good genes. Some people are just naturally blessed with youthful looks, and he might be one of them. Tsubaki - Kakashi-sensei seems like a really laid-back person, and stress can really take a toll on your physical appearance. Maybe his relaxed attitude helps him stay young. Yodo - Kakashi-sensei has seen so much in his life as a ninja, so maybe his experiences have somehow influenced his aging process. It's like they say, "what doesn't kill you makes you stronger." Wasabi - Maybe it's just pure luck. Some people are lucky enough to age slower than others, and Kakashi-sensei might be one of them. Kawaki - Kakashi has always been known for his mysterious and enigmatic nature. Maybe his eternal youth is just another one of his secrets that he keeps hidden from everyone.