After leaving the Hokage's office, Uzumaki Gamu went to find his youngest sister-he could sense her chakra, so she probably hadn't gone along to plant trees!
Without coordinates, he couldn't teleport straight there with the Dimensional Formation, so Uzumaki Gamu had to walk!
When he reached Hashirama's house, Uzumaki Gamu knocked gently. After a short wait, a six-year-old child came to open the door!
The child looked at Uzumaki Gamu and asked politely, "Excuse me, who are you looking for?"
"Hey, kiddo, I'm your uncle!" Uzumaki Gamu ruffled the child's hair-yes, this was Hashirama and Mito's son, Senju Mugen. Another three years had passed, and he was now six... just about old enough to start elementary school!
At Uzumaki Gamu's words, Mugen's eyes filled with confusion-well, he had only been three when they last met, too young to remember much. It was perfectly normal that he didn't remember Uzumaki Gamu.
Seeing the little fellow's bewildered expression, Uzumaki Gamu called into the house, "Mito, stop hiding. You know perfectly well I have sensory abilities~"-this mother was really awful, hiding behind the door just to watch her child get flustered~
Hearing him, Mito stepped out with a chuckle and said, "That's what you get for disappearing for years at a time. Isn't it perfectly normal for your nephew not to recognize his uncle~?"
"Well~ I couldn't help it." Uzumaki Gamu shrugged, then continued ruffling Mugen's hair. "Here, your uncle brought you some snacks~"-Uzumaki Gamu took out the Want Want gift pack he had prepared beforehand.
Well, snacks were the best way to bribe a child this age! (Uzumaki Gamu: If he'd seen Ultraman, I'd have bribed him with an Ultraman gift pack instead.)
Although Mugen didn't know what it was, his instincts told him it was something good, so he accepted it.