An alert was sent to everyone in the Aldera Junior High-school class 8-T13 (made-up, its Izuku and Katsuki's middle school class.) saying that there will be a meet-up. They will meet at the school classroom and catch-up for 30 minutes and then they will go do different activities. This takes place when they are all in their first year of high-school, nobody else in the class had seen or heard that Izuku is no longer quirkless and got into UA. (They don't really watch the news or anything.) Izuku decided to bring his best friend along for the ride, I mean the invite never said that he COULDN'T bring anyone.