yes the neighbor is Grey, but Grey denied that he was actually Aruse and said that he didn't know who Aruse is... so, was Grey lying or not? I will be glad too if Aruse is Grey, but the manga didn't make it conclusive (or maybe I'm too dumb to understand)... ╮( ̄▽ ̄)╭
SAKURAAAAA~~~
ε=ε=(ノ≧∇≦)ノ