Million Smiles

This is the story of an enthusiastic young teacher, Nakai Tarou, whose goal is to make his class be full of smiles! He took over as the teacher of E Class, which was full of problem students. His effervescent optimism and friendliness won over the hearts of his students, and now, at the end of their year with him, they are searching for a way to say goodbye that will express the way he has affected their lives.

(Source: MangaHelpers)