The box-type compact Soul of Korea’s Kia Motors Corp. is strengthening its stranglehold in the U.S. market as its Japanese rivals are suffering sluggish sales, industry data showed Tuesday.

Kia sold 63,635 units of the Soul in the first six months of the year in the U.S., with a market share of 82 percent in the segment, beating other boxes like the Nissan Cube and the Scion xB of Toyota, according to the data.

During the same period, 10,206 units of the Scion xB were sold, while sales of the Cube reached only 4,085 units.

The Soul has enjoyed brisk sales since its debut in 2009, with 37,587 units sold in the year and 102,267 units in 2011. Its monthly sales hit over 10,000 units in 2012, far outselling its Japanese rivals.

With the slump in sales, Toyota decided to discontinue the once-popular box car in the U.S. market without a further model change, according to industry sources.

The Scion xB made its debut in late 2002 and started a trend of “boxy cars” worldwide, but its sales fell from a high of about 61,000 units in 2006 to about 17,000 in 2011.

The source also said that Nissan will stop offering two Cube trims of the 1.8 Base for the 2013 model and the 1.8 Indigo Limited Edition in the U.S. market.

“The Soul is our flagship model for the U.S. market. We expect the Soul to boost our sales in the U.S. in the coming years,” said a company official.

Kia sold 550,625 units in North America last year, up 34.2 percent from a year ago. (Yonhap News)