KARIYA, Japan — To parts supplier Denso Corp., Toyota is indisputably ichiban, or No. 1.
Toyota Motor Corp. is Denso's top shareholder, its biggest customer and the exclusive buyer of nearly all of Denso's world-first technology, such as components for fuel-saving hybrids.
That relationship is not about to change anytime soon, even as Denso strives to be a more global player, said President Koichi Fukaya.
"Honestly speaking, it's Toyota first," Fukaya said here last week at company headquarters. "Toyota is our biggest shareholder and originally like our father."
Toyota holds a 21 percent stake in Denso and accounts for half of the auto supplier's sales.
Denso posted global sales of $30.6 billion in the fiscal year ending March 31, up 13.2 percent from the previous year.
Fukaya expects Denso's sales of hybrid components, such as converters and battery monitoring units, to more than double over the next three years. But all of that goes to the Toyota group.
Denso doesn't supply the parts to anyone else, despite surging global demand for hybrids. Toyota's proprietary rights to the technology prevent Denso from selling to outsiders.
Not that Denso is all that eager to sell cutting-edge products to potential Toyota rivals. Fukaya said Toyota raked Denso over the coals for developing a high-pressure diesel common-rail system for Mazda's MPV minivan in 2002.
"Toyota scolded us: 'Why are you selling this world-first technology to others?' " he said.
But Denso is trying to diversify its customer base. Sales outside Japan now account for about half of Denso's total, up from 43 percent in 2003.
General Motors is one company where Denso sees potential for growth. About 4.1 percent of Denso's sales now come from GM, compared with 2.7 percent in 2003. Denso aims to make more GM inroads with Opel in Europe and Daewoo in South Korea.
But for the other Detroit players, the numbers are still paltry. Ford Motor Co.'s share of Denso's sales has languished around 1 percent for the past five years, while Chrysler LLC's has fallen from 3.5 percent to 2 percent.
Denso's major products are heating and air-conditioning parts, electronic powertrain controls, starters, alternators and navigation devices.