Police said Tuesday they have arrested four men in two separate cases for allegedly trying to extort money out of Softbank Corp. and an affiliate with confidential client data leaked from its Yahoo BB Internet connection service.

The Metropolitan Police Department arrested Hiroshi Mori, 65, and Seiji Takeoka, 55, of Tokyo, as well as Teruaki Yuasa, 61, from Hakodate, Hokkaido, on suspicion of trying to extort several billion yen from a Softbank executive. They reportedly told police they had obtained information on 4.6 million Yahoo BB users.

The group allegedly demanded on Jan. 21 that the executive pay 2 billion yen to 3 billion yen in cash and sign a "consulting" contract with them carrying a monthly fee of several million yen. They showed him a printout of information on 138 customers, according to the police.

In a separate case, Hiroyuki Kimata, 31, from Iwakura, Aichi Prefecture, was arrested for allegedly trying to extort more than 10 million yen out of Softbank affiliate Softbank BB Corp. in the same fashion, they said.

The police said the three men and Kimata are not connected and officers are investigating how they obtained the confidential information.

Softbank said in January that personal information about 242 customers was leaked. The information included users' names, addresses, telephone numbers, e-mail addresses and when they signed up for Yahoo BB.