Three elite law firms have won roles on a joint venture between a subsidiary of Japanese investment giant SoftBank and U.K. online retail group The Hut Group (THG) in a multi-billion dollar deal.

SoftBank’s SB Management has bought an option for a nearly 20% stake in THG Ingenuity, an ecommerce business belonging to THG, in a deal that values the entity at around $6.3 billion.