My current fav Jpop group is Sakamoto twin also know as On/Off (well second fav after AAA)
As you can see from this picture on the left is Naoya and on the right is Kazuya
What I like about them is their voice almost similar(twin harmony) and also nice.
It hard to tell their voice apart , I found that Naoya's voice more soft that Kazuya, but their sound the same almost every time (I can only identify which voice belong to who on futatsu)
And last week I manage to get last copy of Futatsu No Kodo To Akai Tsumi [w/ DVD, Limited Edition] from amazon.jp