Masayuki Kuwabara, 72, of Nagoya, and Cebu-based Yushiyaki Mewa, 49, were gunned down by two motorcycle-riding men as the victims chauffeur-driven car stopped at an intersection on the outskirts of the city, police chief Hiram Binatiro said.
Kuwabara, who was in the backseat, was shot in the head and died on the spot, while Mewa was in critical condition after taking a bullet in the face, Binatiro said.
Kuwabara was a frequent visitor to Cebu, where he bought fiberglass for his company in Japan, Art Hawkinson. Mewa lives in Cebu and acts as his technical consultant, he said.
"We are pursuing a business rivalry angle. We also heard reports that Kuwabara owed a lot of debts here," Binatiro said without elaborating. "We are continuing with our investigation."
According to Mewas driver who survived the attack, the suspects also seized a brown paper envelope from Kuwabara, the police chief said.
The attack came just days after President Arroyo visited Tokyo and vowed to address concerns on law and order raised by Japanese businessmen in the Philippines.
The Japanese Chamber of Commerce in Manila last month warned the Philippines was losing its competitive edge to neighbors such as China, Vietnam and Thailand.
The group noted that apart from providing Japanese investors "a good state of law and order," these countries were also giving investment incentives.
In February, six Japanese engineers working on a road project also in Cebu narrowly escaped death in an ambush that police consider a murder attempt. A suspect in the incident has been detained.
Japan is the second largest foreign investor in the Philippines after the United States. Jaime Laude