Anata ni Kika Setai Uta ga Arunda

When we were 17 we looked at our teacher who was 27 with arrogance but time flies and before we knew it, we were 27 too. We didn't know how hard life could be 10 years later. We didn't know we would meet each other and our teacher again in that future. (Source: Japanese = Hulu || Translation = MyDramaList)