Yosef Anthony Stein was born in Chicago, Illinois on August 29th, 2006. Sukina Stein is his older sister by almost 5 years, although that didn't stop them from becoming close as siblings. She's how he found most of his interests and passions, from comic books to video games. He's taken some interests and gotten more invested in them than she has, notably video games. They're very close with each other, and this was largely due to the death of their mother when Anthony was four years old, in December of 2010. After that, he looked up to Sukina even more, in the sense of a rolemodel but not also for emotional support. There's very little he hasn't told Sukina, except for a few secrets.

Anthony moved to New York City with his family in before the start of his 7th grade year, and quickly made friends, especially with Kiku Nakatsukasa (who he would later find out was the younger sister of a certain guy who had a crush on his older sister). They're a mischevious duo, and are both friends with other younger siblings of some of the main characters in Middle Part. They aren't involved in any superhero shenanigans, but are involved in plenty of middle school drama.