TOKYO (Reuters) - Japan's Mizuho Financial Group will take a 15% stake in Rakuten Group subsidiary Rakuten Card for 165 billion yen ($1.06 billion) in a further deepening of the two companies' strategic alliance, they said on Wednesday.

The share transfer is planned for Dec. 1, they said.

The two groups agreed late last year for Mizuho to raise its stake in group firm Rakuten Securities to nearly half as Rakuten Group struggled financially, dragged down by its unprofitable mobile network unit.

Rakuten said the sale of the Rakuten Card stake would result in a special profit of 159.35 billion yen at the unconsolidated level in the financial year ending in December.

($1 = 155.1000 yen)

(Reporting by Chang-Ran Kim; Editing by Muralikumar Anantharaman)