Roberto Arvelo (ロベルト高城, Roberuto Takashiro) is returned from Brazil and becomes Laura's classmate. Roberto is a very arrogant but talented soccer player on the school soccer team. He often argues with Travis and Laura, but Roberto is really a nice guy who is often misunderstood. He is also a dog lover, and is fond of Laura's dog Brandy. He has a puppy named Samba who debuted in Who Stole My Shoe? Many fans believe he has a small crush on Laura.
Though he was stubborn and egotistical up on his first encounter, he revealed he was merely misunderstood and actually a nice guy. He says he does not like rodents and appeared rather distressed when he met Hamtaro for the first time calling Hamtaro a rat after "saving" Laura and Kana from a speeding car whilst they were crossing the road. He is a part of the school soccer team, though he is very good at the game he sometimes forgets to pass the ball as seen in In A Pinch, A Rival Appears! later in the episode Hamtaro, Oxnard and Boss search to teach him a lesson for insulting Hamtaro. He then saves them from a cat that was chasing them, but it becomes apparent that he can not tell the difference between rodents after calling them "chipmunks". In a Halloween episode, he dresses up Samba as a gremlin by putting a mask on the puppy, succeeding at scaring Laura and Kana who had been late to his Halloween party.