These rankings where taken based on the number of booths who signed up to sell books for that pairing at the event.
1. America/England (Hetalia, 221 spaces)
2. Hibari/Tsunayoshi (Reborn!, 204 spaces)
3. Suzaku/Lelouch (Code Geass, 191 spaces)
4. Roy/Edward (Full Metal Alchemist, 143 spaces)
5. Abe/Mihashi (Ookiku Furikabutte, 138 spaces)
6. Kakashi/Iruka (Naruto, 129 spaces)
7. Koizumi/Kyon (Suzumiya Haruhi series, 125 spaces)
8. Lockon/Tieria (Gundam 00, 118 spaces)
9. Athrun/Kira (Gundam SEED/Destiny, 107 spaces)
10. Gintoki/Hijikata (Gintama, 101 spaces)
Considering they were only ranked 8th at Winter Comiket back in December- they made a huge jump to get into that number one slot. Awesome!