Which episode features Natsu joining Fairy Tail and Erza teaching him to write?


I know there was one episode where it says how Natsu joined Fairy Tail and
then he found some mission and Erza started teaching him reading and writing,
but I forgot which one it was....




I think you're referring to `Episode 27`. Also note that that was an anime
only scene, and you aren't quite remembering it right. Natsu already knew how
to read thanks to Igneel. Erza just expanded his vocabulary.

