Sensei Ote wo Douzo

This one-shot is a short but sweet story about a girl named Hina who has suffered from social anxiety ever since she was a kid. Back then, her nursery school teacher Satoru-sensei encouraged her and helped her face her fears. Hina later grew up to become a nursery school teacher herself thanks to Satoru-sensei's influence. But when Hina gets a job at the same nursery school as him, Satoru-sensei doesn't seem to recognize her at all? Furthermore, her old fears start to return when Hina learns that she and Satoru-sensei will be in charge of MC'ing a school assembly!!

Source: My Anime List