When Izuku is in early middle school, his dad stops sending money to Inko. Inko finds out about a job in the Mie prefecture. This seems perfect, because the apartments in the area are also cheaper than in Musutafu. She gets the job and they move.
At his new school, Izuku befriends Ochako. When he starts hanging out at her place, her dad takes a liking to him and becomes the father figure he never had. Whenever he shows Ochako how to build or fix something, Izuku is always included. With time, Izuku grows to really love construction work, and he realizes what a valuable career it is to the community. He still tries for UA, but when he fails, he sees Uraraka off with a smile and then accepts her parents' offer to intern at their construction company while in high school. Once he graduates, they hire him full-time.
Fast forward, and pro hero Shouto has been quickly climbing the ranks and is ready to open his own agency. His dad buys a very modern, expensive building for him. Shouto refuses it and instead buys a place that is quite literally crumbling apart. He wants to hire a construction team to turn it into something the surrounding neighborhood can be proud of.
As it turns out, his good friend Uravity has some connections in construction. Next thing Izuku knows, he's been entrusted with his first major project. He's to head the construction of the new Shouto Agency.