How to bribe a Japanese ambassador

Twenty or so years ago, reading a magazine at a bookstore, I came accross an article describing how Japanese trading houses bribed Japanese diplomats posted at Japanese embassies in developing countries. At that time, Japan's official development assistance (ODA) towards developing countries was still increasing, and bribery from Japanese companies which sought the chances of earning contracts of ODA projects to the politicians and government officials were occasionally exposed in the media. The article cited an anonymous person working at a Japanese trading house who said that a convenient way to bribe Japanese officials was to play golf with them. People who play golf sometimes bet something, such as a small amount of money or a meal, on their golf match. By using this custom as a disguise, Japanese private companies could tacitly and safely offer some money to government officials, who would reject receiving outright offering of money or gifts.
This article reminded me of my former boss at the Institute of Developing Economies. I was still in the 20s, and my boss then was a scholar specialized in Myanmar. Besides doing research he was active in the Japanese ODA scene in South and South East Asia. Although I couldn't really understand why a scholar cound be so influential in governmental projects, I could feel that he was welcomed by Japanese contruction companies and trading houses which were building roads and bridges in South and South East Asia funded by Japan's ODA. Once, when I was travelling with my boss in South East Asia, he told me that he was going to play golf with a Japanese ambassador to a certain Asian country. At that time I only thought that my boss must be a great person, being golf mates with a famous ambassador. This diplomat wrote many books regarding Japanese diplomacy and famous for his hawkish views.
After reading the article, however, I understood why my boss had the glory of playing golf with an influential ambassador. For a governmental official, it might be risky to play golf with people working for private companies, because it would induce suspicions. But playing golf with a scholar working for a government-related institute would be no problem at all. At the golf club, there of course will be some other "friends", who will join together to play golf with the two, and tactically lose the match, offering some gifts to the ambassdor with a smile. Well, that part of course is my guess with no evidence. All I know is that the ambassador and my boss were no longer golf mates after the ambassador had returned to Japan.