Ranking of Korean groups' debut sales in Japan

Ranking of Korean groups' DEBUT SALES in Japan
This is ranked based on sales in their 1st week of Debut.

01. SNSD "Genie" 44,907
02. MBLAQ "Your Luv" 40,281
03. KARA "Mister" 29,238
04. Beast "Shock" 28,532
05. Big Bang "Heaven" 26,039
06. BoA "ID Peace B" 14,740
07. Supernova "Kimi Dake Wo Zutto" 8,542
08. ZE:A "Love letter/My only wish" 8,273
09. SES "Meguriau Sekai" 7,390
10. Se7en "Hikari" 7,303
11. 4MINUTE "Muzik" 4,241
12. FT Island "One Way" 4,043
13. CN Blue "The Way" 3,353
14. DBSK "Hug" 2,502
15. Cheon Sang Ji Hee (CSJH/ The Grace) "Boomerang" 967

Source: bestiz + absolutemblaq
* edited on Supernova's debut single

*In my opinion, this is just numbers. They do have difference in terms of debut time. Some of them debuted when K-Pop is not as big as it is now in Japan, and also on how strong their fanbase when they debuted.
So, this is just a reference on how many they sell on their first week after debut.