On the opening credits thats what it said in japanese...
"Tonari no Hito" is "Neighbour" and "13go" is "Number 13"The Japanese DVD has the English Title on the cover.
Both have the same meaning: Neighbour No. 13 Rinjin 13-go = Neighbour number 13 Tonari no hito 13-go' = person of next door number 13, e.g. Neighbour number 13