Police carried out a 45-minute search here Friday of Yamaguchi-gumi's headquarters over allegations that Japan's largest yakuza group was involved in loan-sharking.
Police suspect billions of yen in profits generated by illegally high interest charged on loans were transferred to the underworld group, investigative sources said.
They believe Yamaguchi-gumi was at the top of a pyramid-style nationwide loan-sharking system, the sources said. Total earnings from the scheme probably amount to hundreds of billions of yen, they said.