It's likely that Tsunade's age didn't really show before Kushina died, so that jutsu was probably invented much later, when she cut all ties to the Leaf Village. With that being said, it's such a non-issue that you can probably justify him having this idea and having the chakra control to perform it. Tsunade is likely not the first person to consider using chakra to constantly maintain the image of youth, she's just the only character insecure enough about aging to do it and invest time in learning how. If this character disappeared before Kushina died, Tsunade would've left the village after losing her little brother and lover, and it doesn't sound like your character tried to stick around. If she did teach him a thing or two about medical ninjutsu, it would have to be before the war, and she would've left the village some time after it; Tsunade didn't mess around with medical procedures after her lover died with his blood covering her, and the phobia set in.
This guy returning in the Boruto generation means he missed out on a lot of world-changing events. This is not the same world he would have left. The villages are at peace; the world is trying to maintain it for as long as possible... and also there are, like, aliens n' shit running around. The Kage in power when he disappeared are dead or retired, putting new faces in their place. Any other characters he knew are either dead or aged normally. Even businesses and the people that ran them are likely closed. It's going to be a shock, waking up from a comatose state to rediscover a world that moved without his presence. His sister was killed, that's never good, he's going to need to process that if he didn't before entering a comatose state. There's a lot you need to consider, yes.
Linking goofiness and a taste of food isn't inherently a bad thing, but it isn't a necessity. Naruto was a goofball because it gave him positive attention, which the entire village neglected to give him; he was extremely depressed and isolated, and turned to humor and acting out because laughing at his antics is a lot better than being afraid to talk to him. He can like ramen without inheriting a fondness for it via blood connection, too. Some family members have things in common without blood being a part of that; it's perfectly fine if both these characters enjoy ramen, and relations don't need to have anything to do with it. He became the man he is without his uncle; tying traits to him isn't a necessity, but if you believe it makes your character better in some way, that's your call. Nothing wrong with wanting to make ramen though, you can lean into creating ramen as a hobby for the character. Jiraiya wrote smut novels; Kakashi read smut novels; Ino tends to plants; Shikamaru plays Shogi; your character can cook and use that as another means of bonding with the nephew he didn't get to see grow up.
Depending on the universe, Alfred doesn't take anything from anyone either. He's meant to demonstrate professionalism and rationality. That doesn't mean he's a chump you can insult and expect to get away with it. If your character would rather maim someone than engage in a battle of wit when disrespected, that's certainly the kind of darkness you can imply.
If his eyes can easily give away his inhuman nature, does he have no illusionary abilities to conceal it? If he had years to perfect his abilities, has he perfected a disguise that wouldn't attract unwanted attention? It might be easier for him to blend in if he isn't ungodly handsome, and he diminishes his appearance on purpose to appear like the average citizen on Earth. Nothing designer. Nothing expensive on his person. He doesn't need to be a hobo, but if he's too attractive, that encourages attention. You need to decide if he can mask this in some way, or if he's going to be all, "Well, I'm too sexy for my shirt," and just walk around being hot but not wanting people to realize he's hot... which probably ain't gonna work, because hot people get attention whether they want it or not.
He wants to pay his respects and "be done with it" -- "just a quick trip". This is his father. Did he have a strong relationship with his father in life? Was his father there for him when he grew into a man? Did his father even KNOW about him, or did his mother conceal that fact from him for the remainder of his life? Does he resent his father for dying? For being human? For leaving him?
All these question aside, I still need to know how meeting Alfred and whoever accompanies him turns him into a butler. Why does the super hot magical guy meet his uncle and decide on becoming a butler, of all things? What did he aspire to before meeting Alfred? Does he love to serve people regardless of his powers? Does he want to be of use to people, and if so, why, specifically, a butler, when someone who is so powerful could help people in other ways rather than one specific family? There has to be a reason he turns to this path.
Alfred can learn to love the nephew he never knew he had without him becoming a butler, too. He can help him find a place in Gotham City if he wants a fresh start. And with Alfred's connection to Bruce, I'm sure a job referral from Bruce Wayne himself could go a long way in many industries in Gotham City. But he must prove himself, too. And if he's never held a job in the mortal world, he's going to have to explain how he's survived this long. Is he going to lie to his uncle about who he really is forever, or will he be forced to be truthful when certain details aren't adding up? Alfred's a butler, he's not an idiot; you don't butler for Batman and not sense something is amiss.
Think on it.
Your support makes Blue Moon possible (Patreon)
