Smith family

The Sumisu-ke (スミス家) was one of several families that lived within the walls. It was the family where Commander Erwin Smith hailed from.

Story
Mr. Smith was a teacher and had his son as one of his pupils. After Erwin asked his father a question during class, Mr. Smith eventually told his son a dangerous theory. Official history books being full of contradictions and mysteries, Mr. Smith believed that humanity memory has been wiped out at some point, which might explain there is no story or memories of the walls construction. This theory cost his life to Mr. Smith but encouraged Erwin to seek out the truth about the world's origins and prove his father's guess was correct.